| Dokumendiregister | Terviseamet |
| Viit | 13.2-7/25/1835-1 |
| Registreeritud | 12.03.2025 |
| Sünkroonitud | 13.03.2025 |
| Liik | Sissetulev dokument |
| Funktsioon | 13.2 Nakkushaiguste labor |
| Sari | 13.2-7 NHL kirjavahetus |
| Toimik | 13.2-7/2025 |
| Juurdepääsupiirang | Avalik |
| Juurdepääsupiirang | |
| Adressaat | Francis Cricki Instituut |
| Saabumis/saatmisviis | Francis Cricki Instituut |
| Vastutaja | Liisi Kink (TA, Peadirektori asetäitja (2) vastutusvaldkond, Rahvatervise labor) |
| Originaal | Ava uues aknas |
Dear Liisa, Marlen, Johanna and colleagues,
I hope you are well. Here are the results of the analyses of the influenza specimens you kindly shared with us for characterisation from Estonia in August 2024.
Along with the analyses, we have also included a high-level summary of influenza circulation and evolution during the South hemisphere influenza season 2024.
We will be soon preparing another report for samples received during the North hemisphere influenza season 2024-2025.
Should you need any additional information, please don’t hesitate to contact us, we will be very happy to assist.
I look forward to continuing to work closely with you and thank you again for your support and collaboration.
With very best wishes,
Monica
On behalf of the WIC team
Dr Monica Galiano
Head of Molecular Testing and Genomics
WHO Collaborating Centre for Reference and Research on Influenza,
The Francis Crick Institute
1 Midland Road
London NW1 1AT
UK
Tel: +44 203 796 0563
Email: [email protected]
The Francis Crick Institute Limited is a registered charity in England and Wales no. 1140062 and a company registered in England and Wales no. 06885462, with its registered office at 1 Midland Road London NW1 1AT
Country Report: Estonia Worldwide Influenza Centre, WHO CC for Reference and Research on Influenza
The Francis Crick Institute, 1 Midland Road, NW1 1AT
February to August 2024
Prof. Nicola Lewis (Director ‑ WIC)
Dr. Ruth Harvey (Deputy Director)
Dr. Monica Galiano (Head of Molecular Testing and Genomics)
Dr. Alex Byrne
Dr. Zheng Xiang
Ms. Christine Carr, Ms. Burcu Ermetal
Dr. Karen Cross, Ms. Aine Rattigan
Ms. Alice Lilley, Mr. Michael Bennett
Ms. Chandrika Halai, Ms. Becky Clark, Mr. Lorin Adams
Dr. Tanya Mikaiel, Ms Abi Lofts, Dr. Alize Proust
Tel:0203 796 0563 (WIC) or [email protected]
Email: [email protected]; [email protected]; [email protected];
Formore information aboutwhatwehave observed over the last twelvemonths please see our reports for Septem‑ ber 2023 and February 2024. All of our reports since 2003 are available at https://www.crick.ac.uk/partnerships/w orldwide‑influenza‑centre/annual‑and‑interim‑reports
1
Influenza by type/subtype: Geographical distribution of seasonal influenza viruses with collection dates from February through to September 2024 as deposited in GISAID, coloured by Type/subtype. Geographic markers scaled to detection proportions.
As of September 2024, in the Northern hemisphere influenza activity in temperate countries remained at interepi‑ demic levels. Activity continued to increase in a few countries in Middle Africa.
In the Southern hemisphere, influenza activity remained elevated in some countries in South America, Eastern Africa, Southern Africa, and Oceania. Activity declined or was similar compared with the prior report across the Southern hemisphere.
The relative proportions of A/H1N1, A/H3N2 and B/Victoria varied by geographic region, with predominance of A/H3N2 in the Americas, Africa, South East Asia, Western Pacific region and Russian Federation, and some pre‑ dominance of A/H1N1 in Europe, Middle East, South Africa, Madagascar, India and Brazil. Some countries showed predominance of B/Victoria such as Canada, UK, Portugal, Syria, Ukraine, Mali, Japan and Mongolia, as indicated by the different colours in the pie charts by country.
2
Genetic diversity: Plots showing genetic diversity of A/H1N1, A/H3N2 and B/Victoria that underwent sequencing during the reporting period. A(global) B(WHO region)
3
Phylogenetic analyses: A/H1N1 6B.1A.5a.2a and 6B.1A.5a.2a.1 clade viruses both continued to circulate with differing relative proportions depending on region, with an overall predominance of 5a.2a viruses.
Globally, there is predominance of clade 5a.2a except in the Americas where there is a slight predominance of clade 5a.2a.1. In Europe, viruses from clade 5a.2a were detected with much higher frequency than clade 5a.2a.1.
Within the 5a.2a viruses, characterised by substitutions K54Q, A186T, E224A, R259K and K308R, several sub‑ clades were observed: subclade C.1 defined by substitution I418V which split into two further subclades: C.1.8, characterised by V47I with I96T in most sequences, and C.1.9, with substitution K169Q; the majority (>80%) of H1pdm viruses sequenced globally belong to subclade C.1.9, with viruses from C.1.8 as a minority subclade mostly observed in Europe. Minor subclades C.1.7 with substitution I533V and C.1.7.2 with T120A and K142R were circulating in Indonesia in low proportions.
Within the 5a.2a.1 viruses, characterised by substitutions P137S, K142R, D260E, T277A, E356D and N451H, there are twomain groups of viruses: major subcladeD (former C.1.1.1)with T216A representedby A/Victoria/4897/2022, which has split into four subclades: D.1 with R45K, D.2 with R113K and V427I, D.3 with T120A and I372V and D.4 with T120A. Of these, only subclade D circulates in significant proportions, albeit predominating only in the Americas. Subclade C.1.1 is a minor clade within 5a.2a.1 viruses with no additional substitutions represented by A/Wisconsin/67/2022, which has been detected in significant proportions only in Iceland.
All A/H1N1 viruses from Estonia belong to clade 5a.2a, of which 6 clustered within subclade 5a.2a (C.1.8), 6 within subclade 5a.2a (C.1.9) and 2 within subclade 5a.2a (C.1).
4
Global geographical distribution of influenza A/H1N1 genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade. Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of A/H1N1 viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the H1 HA gene Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
5
6
Phylogenetic analyses: H3N2 Clade 3C.2a1b.2a.2 (renamed as 2) predominated since February 2023 in all geographic regions where A/H3N2 circulated.
During this reporting period, the great majority of H3 viruses detected belong to clade 2a.3a.1, which share substitution E50K with clade 2a.3a and present additional substitutions I140K and I223V (subclade J, vaccine reference A/Thailand/8/2022). Subclade J split into 4 further subclades: of these, subclade J.2 (reference A/Sydney/878/2023) characterised by N122D (‑CHO) and K276E became the dominant subclade, predominating in the majority of continents with >90% frequency. Subclade J.1 (reference A/Sydney/856/2023) characterised by I25V, V347M with additional I418V (in some viruses) was detected in minor frequencies (<10%) in Europe, South‑East Asia, Africa and Oceania. Minor subclade J.4 characterised by Q173R, K276E and some viruses with K189R predominated in West Africa earlier during the season.
Clade 2a.3a (subclade G.1.3.1, reference A/Finland/402/2023) with substitutions K276E and V347M was detected in West Africa earlier during the season.
All A/H3N2 viruses from Estonia belong to clade 2a.3a.1, of which 9 clustered within subclade 2a.3a.1 (J.2) and 2 within subclade 2a.3a.1 (J.1).
7
Global geographical distribution of influenza A/H3N2 genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade.Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of A/H3N2 viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the H3 HA gene. Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
8
9
Phylogenetic analyses:
Influenza B viruses B/Victoria lineage Clade V1A.3a.2 viruses characterised by substitutions A127T, P144L, N150K, G184E, N197D (‑CHO), K203R and R279K (B/Austria/1359417/2021, subclade C) predominated since February 2023 in geographic regions where B/Victoria‑lineage viruses were detected.
During this reporting period, only a minority of B/Victoria viruses were detected and characterised in Europe. Within V1A.3a.2, subclade C.5 with D197E represents the majority of influenza B viruses characterised during the current influenza season. The most frequent subclades observed within C.5 are: C.5.1 with E183K represented by B/Catalonia/2279261NS/2023, as the dominant subclade predominating in the Americas, Portugal, Ukraine, New Zealand and detected in several other countries in minor proportions; C.5.6 (B/Norway/08717/2023) with D129N predominating in South East Asia, Middle East, South Africa and some European countries; C.5.7 with E183K and E128G predominating in China, Japan, Australia, Russian Federation, Mongolia and some countries in Europe. Minor subclades such as C.5.4 (B/Slovenia/924/2023) with V117I, E128K, A154T and K326R were detected in Chile and the US, and C.5.5 (B/Paraguay/2102/2023) with R80G, E184K were detected in North America in very low proportions.
Outside of C.5 viruses, other subclades such as C.2 (T182A, D197E, B/Netherlands/10335/2023) and C.3 (E128K, A154E, S208P, B/Norway/5216/2023) were detected in low frequency in West Africa and Madagascar earlier during the season.
All B/Victoria viruses from Estonia belong to clade V1A.3a.2, of which 9 clustered within subclade V1A.3a.2 (C.5.7), 4 within subclade V1A.3a.2 (C.5.1), 4 within subclade V1A.3a.2 (C.5.6) and 2 within subclade V1A.3a.2 (C.5).
B/Yamagata lineage No B/Yamagata lineage viruses have been detected since March 2020.
10
Global geographical distribution of influenza B/Victoria genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade.Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of B/Victoria viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the B/Victoria lineage HA gene Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
11
12
Phenotypic analyses Haemagglutination inhibition (HI) assay data: ferret antisera raised against vaccine recommendations
H1 Summary HI titres show that NH 2023‑24, 2024‑25 and SH 2024 strains, cell‑based A/Wisconsin/67/2022 and egg‑ based A/Victoria/4897/2022, generally recognised both 5a.2a and 5a.2a.1 clade viruses well. Some four‑fold drops were observed with the cell‑ based A/Wisconsin/67/2022 strain that were not seen with the egg‑based A/Victoria/4897/2022.
H3 Summary HI titres show that the SH 2024 and NH 2024‑25 vaccine strains, egg‑based A/Thailand/08/2022 (2a.3a.1 (J)) and cell‑based A/Massachusetts/18/2022 (2a.3a.1 (J)), demonstrate reduced recognition against a significant number of samples in the J.2 and J.4 subclades. The cell‑based SH 2024 and NH 2024‑25 vaccine strain, A/Massachusetts/18/2022 (2a.3a.1 (J)) recognised most viruses tested within 2‑fold, but showed significant drop in titre to some J.2 and all J.4 viruses tested to date.
Influenza B summary All V1A.3a.2 viruses tested were well recognised by antisera raised against the B/Austria/1359417/2021 vaccine virus.
Antiviral susceptibility All tested viruses were susceptible to neuraminidase inhibitors (NAI) by phenotypic testing and no geneticmarkers for reduced inhibition by NAIs were identified in NA sequences derived from clinical specimens.
Phenotypic testing for susceptibility to Baloxavir marboxil showed no reduced inhibition among all tested viruses. For all viruses where PA gene sequencing was successful, no markers associated with reduced inhibition by balox‑ avir marboxil were identified.
13
HI Tables: H1
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022 A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a
(C.1.9) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1 (C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 2560 2560 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1.9) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 1280 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 1280 1280 1280 2560 640 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 1280 1280 2560 1280 1280
TEST VIRUSES 244843 A/Estonia/177563/2024 5a.2a (C.1) 2024-01-15 MDCK1 2560 2560 2560 2560 640 244837 A/Estonia/177712/2024 5a.2a (C.1) 2024-01-21 MDCK1 2560 2560 2560 2560 1280 244878 A/Luxembourg/3787860/2024 5a.2a (C.1.9) 2024-02-22 SIAT1 2560 2560 2560 2560 1280 244835 A/Estonia/179137/2024 5a.2a (C.1.9) 2024-03-11 MDCK1 2560 2560 2560 2560 1280 244596 A/HongKong/783/2024 5a.2a (C.1.9) 2024-03-12 MDCK 2/MDCK1 1280 2560 1280 1280 640 244871 A/Luxembourg/248452/2024 5a.2a (C.1.9) 2024-03-13 MDCK1 2560 1280 2560 1280 1280 244869 A/Luxembourg/5023242/2024 5a.2a (C.1.9) 2024-03-26 MDCK1 1280 2560 2560 1280 1280 244873 A/Luxembourg/3226762/2024 5a.2a.1 (C.1.1) 2024-02-02 MDCK1 2560 2560 5120 2560 2560 244630 A/Croatia/1366/2024 no sequence 2024-02-21 MDCK2 1280 1280 1280 1280 640 244628 A/Croatia/1533/2024 no sequence 2024-02-29 MDCK2 640 640 1280 640 640
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = Not Done SH 2023
SH 2024 NH 2024-25
Table H1-18. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-11)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
14
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a (C.1) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1
(C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 1280 1280 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 2560 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 1280 1280 2560 2560 1280 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 2560 2560 2560 2560 2560
TEST VIRUSES 244391 A/Spain/2606/2023 5a.2a (C.1) 2023-12-29 MDCK1 2560 2560 2560 2560 2560 244387 A/Spain/1780/2024 5a.2a (C.1) 2024-02-04 MDCK1 2560 2560 2560 1280 1280 244389 A/Spain/2201/2024 5a.2a (C.1.8) 2024-02-01 MDCK1 2560 2560 2560 2560 1280 244386 A/Spain/1814/2024 5a.2a (C.1.8) 2024-02-04 MDCK1 1280 1280 1280 1280 640 244832 A/Estonia/178804/2024 5a.2a (C.1.8) 2024-04-03 MDCK2 5120 5120 2560 2560 1280 244388 A/Spain/1810/2024 5a.2a (C.1.9) 2024-02-02 MDCK1 2560 2560 2560 2560 1280 244384 A/Spain/1720/2024 5a.2a (C.1.9) 2024-02-06 MDCK1 2560 1280 1280 1280 640 244382 A/Spain/1828/2024 5a.2a (C.1.9) 2024-02-10 MDCK1 2560 2560 2560 2560 1280 244938 A/CAT/2167458NS/2024 5a.2a (C.1.9) 2024-03-05 C1/MDCK1 5120 2560 2560 2560 2560 244937 A/CAT/3546125NS/2024 5a.2a (C.1.9) 2024-03-11 C1/MDCK1 2560 2560 2560 2560 1280 244934 A/CAT/3547217NS/2024 5a.2a (C.1.9) 2024-03-25 C1/MDCK1 2560 1280 2560 2560 1280 244383 A/Spain/1817/2024 5a.2a.1 (D) 2024-02-06 MDCK1 2560 1280 2560 1280 1280 244936 A/CAT/3546363NS/2024 5a.2a.1 (D) 2024-03-13 C1/MDCK1 2560 1280 2560 1280 2560 244935 A/CAT/2174846NS/2024 5a.2a.1 (D) 2024-03-21 C1/MDCK1 2560 1280 5120 2560 2560 244933 A/CAT/3549595NS/2024 5a.2a.1 (D) 2024-04-30 C1/MDCK1 2560 2560 5120 2560 2560 244939 A/CAT/3545504NS/2024 5a.2a.1 (D.2) 2024-03-04 C1/MDCK1 2560 2560 2560 2560 2560
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = SH 2023
SH 2024 NH 2024-25
Table H1-35. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-18)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
15
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a (C.1) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1
(C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 1280 1280 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 2560 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 2560 1280 2560 2560 1280 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 2560 2560 2560 2560 2560
TEST VIRUSES 244846 A/Estonia/177568/2024 5a.2a (C.1.9) 2024-01-11 MDCK1 2560 2560 2560 2560 1280 244884 A/SouthSudan/1041/2024 5a.2a (C.1.9) 2024-05-29 MDCK2 5120 2560 2560 2560 1280 244882 A/SouthSudan/1023/2024 5a.2a (C.1.9) 2024-06-05 MDCK2 2560 2560 2560 2560 2560 244880 A/SouthSudan/1039/2024 5a.2a (C.1.9) 2024-06-07 MDCK1 2560 2560 2560 2560 1280
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = SH 2023
SH 2024 NH 2024-25
Table H1-36. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-24)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
16
HI Tables: H3
Viruses Other A/Albania assachusetts A/Thailand A/Sydney A/Croatia/ A/Croatia/A/Netherlands A/Slovenia A/Lisboa/A/France/IDF- A/Norway/BurkinaFaso information /289813/2022 /18/2022 /08/2022 /856/20230136/RV/20230136/RV/2023 /10563/2023 /49/2024 216/2023PP29542/2023 /12374/2023 /3131/2023
Passage SIAT SIAT Egg SIAT SIAT Egg SIAT SIAT Egg Cell Cell Cell
Ferret number F21/23 F36/23 F34/23 F01/24 F06/24 F16/24 F08/24 F11/24 F15/24 F22/24 F21/24 F32/24
COPY AND PASTE VALUES!! Genetic group Collection Date
Genetic group 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J.1) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.4) 2a.3a.1 (J.4) 2a.3a.1 (J.4)
REFERENCE VIRUSES A/Albania/289813/2022 N122D 2a.3a.1 (J) 2022-12-13MDCK1/SIAT2 1280 320 1280 640 160 160 320 80 320 160 80 40 A/Massachusetts/18/2022 2a.3a.1 (J) SIAT3/SIAT1 1280 640 1280 1280 160 160 320 80 320 320 160 80 A/Thailand/08/2022 2a.3a.1 (J) E3/E1 1280 320 1280 640 320 640 640 320 640 640 160 160 A/Sydney/856/2023 2a.3a.1 (J.1) 2023-09-12 SIAT1/SIAT2 1280 320 640 640 160 160 320 160 320 160 80 80 A/Croatia/10136/RV/2023 S145N 2a.3a.1 (J.2) 2023-12-04 SIAT3 160 80 160 160 160 160 320 320 320 320 80 40 A/Croatia/10136/RV/2023 S145N 2a.3a.1 (J.2) E3 (Am1Al2) 640 320 640 640 640 640 640 640 640 320 320 80 A/Netherlands/10563/2023 S124N 2a.3a.1 (J.2) 2023-11-10 K-MIX2/SIAT3 320 160 320 320 160 320 320 160 320 320 160 40 A/Slovenia/49/2024 N158K 2a.3a.1 (J.2) 2024-01-08MDCKx/SIAT3 40 <40 160 <40 80 40 40 1280 160 <40 40 <40 A/Lisboa/216/2023 S124N 2a.3a.1 (J.2) 2023-12-15 E3 (Am1Al2) 640 320 640 640 320 320 640 320 640 320 160 80 A/France/IDF-IPP29542/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-30MDCK1/SIAT2 <40 <40 40 40 40 80 80 <40 40 80 40 40 A/Norway/12374/2023 2a.3a.1 (J.4) 2023-11-28 SIAT4 160 80 160 160 160 160 320 80 160 160 80 80 A/BurkinaFaso/3131/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-20 SIAT3 80 40 80 <40 80 80 80 <40 80 80 80 80
TEST VIRUSES 244854 A/Estonia/178001/2024 2a.3a.1 (J.1) 2024-01-30 SIAT1 640 320 640 640 160 160 320 80 320 160 80 80 244850 A/Estonia/178187/2024 2a.3a.1 (J.1) 2024-02-13 SIAT1 640 640 640 640 160 160 320 80 320 160 80 40 244860 A/Estonia/177566/2024 2a.3a.1 (J.2) 2024-01-10 SIAT1 320 160 320 160 160 160 320 160 160 160 80 40 244858 A/Estonia/177562/2024 2a.3a.1 (J.2) 2024-01-12 SIAT1 320 80 160 160 160 160 160 80 160 160 80 40 244857 A/Estonia/177610/2024 2a.3a.1 (J.2) 2024-01-15 SIAT1 160 80 320 160 320 160 320 160 160 160 160 80 244855 A/Estonia/177892/2024 2a.3a.1 (J.2) 2024-01-26 SIAT1 320 80 320 160 160 160 320 160 320 320 80 40 244876 A/Luxembourg/6475699/2024 2a.3a.1 (J.2) 2024-02-06 SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244852 A/Estonia/178200/2024 2a.3a.1 (J.2) 2024-02-08 SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244633 A/Croatia/1613/2024 2a.3a.1 (J.2) 2024-03-04 SIAT2 160 40 160 80 80 160 160 80 160 80 40 <40 244849 A/Estonia/179133/2024 2a.3a.1 (J.2) 2024-03-04 SIAT1 320 160 320 160 320 160 320 160 320 160 160 40 244716 A/Ile_de_France/06119/2024 2a.3a.1 (J.2) 2024-05-24 C2/SIAT2 640 160 320 80 320 160 320 160 640 160 80 <40 244798 A/Bangui/172/2024 2a.3a.1 (J.2) 2024-07-11 SIAT1 640 160 640 320 320 320 320 160 320 160 160 40
SH 2024 NH 2024-25
Table H3-22. Antigenic analyses of influenza A(H3N2) viruses (Guinea Pig RBC with 20nm Oseltamivir) 2024-09-10
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
Vaccine
17
Viruses Other A/AlbaniaMassachusetts A/Thailand A/Sydney A/Croatia/ A/Croatia/A/Netherlands A/Slovenia A/Lisboa/A/France/IDF- A/Norway /BurkinaFaso information /289813/2022 /18/2022 /08/2022 /856/2023 0136/RV/2023 0136/RV/2023 /10563/2023 /49/2024 216/2023PP29542/2023 /12374/2023 /3131/2023
Passage SIAT SIAT Egg SIAT SIAT Egg SIAT SIAT Egg Cell Cell Cell
Ferret number F21/23 F36/23 F34/23 F01/24 F06/24 F16/24 F08/24 F11/24 F15/24 F22/24 F21/24 F32/24
COPY AND PASTE VALUES!! Genetic group Collection Date Genetic group 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J.1) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.4) 2a.3a.1 (J.4) 2a.3a.1 (J.4)
REFERENCE VIRUSES A/Albania/289813/2022 N122D 2a.3a.1 (J) 2022-12-13 MDCK1/SIAT2 1280 640 1280 1280 160 160 320 160 320 320 160 80 A/Massachusetts/18/2022 2a.3a.1 (J) SIAT3/SIAT1 1280 640 1280 1280 160 160 320 80 320 320 80 80 A/Thailand/08/2022 2a.3a.1 (J) E3/E1 1280 320 640 640 320 320 640 320 640 320 160 160 A/Sydney/856/2023 2a.3a.1 (J.1) 2023-09-12 SIAT1/SIAT2 640 320 640 640 160 160 320 80 320 160 80 80 A/Croatia/10136/RV/2023 2a.3a.1 (J.2) 2023-12-04 SIAT3 160 80 160 160 160 160 320 160 160 160 80 40 A/Croatia/10136/RV/2023 2a.3a.1 (J.2) E3 (Am1Al2) 640 160 640 640 640 640 640 320 640 640 160 80 A/Netherlands/10563/2023 2a.3a.1 (J.2) 2023-11-10 MDCK-MIX2/SIAT3 320 160 320 320 160 320 320 160 320 320 160 40 A/Slovenia/49/2024 N158K 2a.3a.1 (J.2) 2024-01-08 MDCKx/SIAT3 <40 <40 80 <40 80 40 80 1280 160 <40 40 <40 A/Lisboa/216/2023 S124N 2a.3a.1 (J.2) 2023-12-15 E3 (Am1Al2) 320 160 640 640 160 320 320 320 640 320 160 80 A/France/IDF-IPP29542/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-30 MDCK1/SIAT2 <40 <40 40 <40 40 40 40 <40 40 40 40 80 A/Norway/12374/2023 2a.3a.1 (J.4) 2023-11-28 SIAT4 160 80 160 80 80 160 320 80 160 160 80 80 A/BurkinaFaso/3131/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-20 SIAT3 40 <40 80 <40 80 40 80 <40 40 80 40 80
TEST VIRUSES 244218 A/Catalonia/NSVH102359047/2024 2a.3a.1 (J) 2024-06-07 SIAT2/MDCK1 320 160 320 320 160 160 160 80 80 80 40 <40 244875 A/Luxembourg/2651601/2024 2a.3a.1 (J.1) 2024-02-12 SIAT1 640 320 640 640 160 160 160 80 320 160 80 40 244947 A/CAT/3545207NS/2024 2a.3a.1 (J.1) 2024-02-26 C1/SIAT1 640 320 640 640 160 160 320 80 160 320 80 80 244944 A/CAT/3545572NS/2024 2a.3a.1 (J.1) 2024-03-04 C1/SIAT1 320 160 320 320 80 160 160 80 80 160 40 40 244853 A/Estonia/177999/2024 2a.3a.1 (J.2) 2024-02-03 SIAT2 320 160 320 320 160 320 320 160 320 320 160 40 244945 A/CAT/3545505NS/2024 2a.3a.1 (J.2) 2024-03-04 C1/SIAT1 320 80 320 160 160 160 320 160 320 160 80 40 244946 A/CAT/3545411NS/2024 2a.3a.1 (J.2) 2024-03-04 C1/SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244943 A/CAT/3545938NS/2024 2a.3a.1 (J.2) 2024-03-11 C1/SIAT1 320 80 160 160 160 160 320 160 320 160 80 40 244942 A/CAT/2175033NS/2024 2a.3a.1 (J.2) 2024-03-21 C1/SIAT1 320 160 320 320 160 160 320 160 320 160 80 40 244941 A/CAT/3549065NS/2024 2a.3a.1 (J.2) 2024-04-21 C1/SIAT1 320 80 320 160 160 160 320 160 160 160 80 40 244940 A/CAT/2194631NS/2024 2a.3a.1 (J.2) 2024-05-02 C1/SIAT1 160 80 320 160 160 160 320 160 320 160 80 40 244904 A/SouthSudan/1069/2024 2a.3a.1 (J.2) 2024-07-12 SIAT1 160 80 160 160 160 160 320 160 320 160 80 40 244899 A/SouthSudan/1064/2024 2a.3a.1 (J.2) 2024-07-17 SIAT1 160 80 160 160 160 160 160 160 320 160 80 40 244901 A/SouthSudan/1062/2024 2a.3a.1 (J.2) 2024-07-17 SIAT1 640 320 640 640 320 320 640 320 640 640 320 80 244887 A/SouthSudan/1045/2024 2a.3a.1 (J.2) 2024-07-29 SIAT1 160 80 160 160 160 160 320 160 320 160 80 40 244886 A/SouthSudan/1044/2024 2a.3a.1 (J.2) 2024-07-31 SIAT1 320 160 160 160 160 160 320 160 320 160 80 40
Table H3-36. Antigenic analyses of influenza A(H3N2) viruses (Guinea Pig RBC with 20nm Oseltamivir) 2024-09-19
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
Vaccine SH 2024
NH 2024-25
18
HI tables: Influenza B
Viruses Other B/Bris B/Austria B/Austria B/Austria B/Stock information 60/08 1359417/21 1359417/21 1359417/21 3/22
Passage Egg MDCK Egg G141 Egg G141R MDCK
Ferret number
Sh 539, 540, 543, 544, 570, 571, 5741
NIB F01/21 F40/21 F44/21 F28/22
COPY AND PASTE VALUES!! Genetic group Collection Date Genetic group V1A V1A.3a.2 (C) V1A.3a.2 (C) V1A.3a.2 (C) V1A.3a.2
(C.5)
REFERENCE VIRUSES B/Brisbane/60/2008 V1A 2008-08-04 E4/E3 2560 40 <40 <40 <40 B/Austria/1359417/2021 A127T, P144L, K302R (G141) V1A.3a.2 (C) 2021-01-09 SIAT1/MDCK4 640 1280 640 320 640 B/Austria/1359417/2021 A127T, P144L, K302R (G141) V1A.3a.2 (C) 2021-01-09 E3/E4 320 1280 640 320 640 B/Austria/1359417/2021 A127T, P144L, K302R (G141R) V1A.3a.2 (C) 2021-01-09 E3/E5 320 1280 640 2560 640 B/Stockholm/3/2022 D129G, E183K, D197E V1A.3a.2 (C.5) 2022-03-22 SIAT1/MDCK3 320 640 640 320 640
TEST VIRUSES 244813 B/Estonia/179145/2024 V1A.3a.2 (C.5) 2024-04-03 MDCK1 320 640 320 160 640 244580 B/HongKong/190/2024 V1A.3a.2 (C.5) 2024-06-14 MDCK 1/MDCK1 640 640 320 160 640 244574 B/HongKong/192/2024 V1A.3a.2 (C.5) 2024-06-21 MDCK 1/MDCK1 640 1280 640 320 640 244864 B/Luxembourg/3510796/2024 V1A.3a.2 (C.5.1) 2024-04-25 MDCK1 320 640 320 320 640 244622 B/Croatia/3095/2024 V1A.3a.2 (C.5.1) 2024-06-10 MDCK1 640 640 320 320 640 244625 B/Croatia/1694/2024 V1A.3a.2 (C.5.6) 2024-03-08 MDCK1 640 640 320 320 1280 244867 B/Luxembourg/9513091/2024 V1A.3a.2 (C.5.7) 2024-03-05 MDCK1 320 640 320 320 640 244812 B/Estonia/179138/2024 V1A.3a.2 (C.5.7) 2024-04-05 MDCK1 320 640 320 320 640 244811 B/Estonia/179136/2024 V1A.3a.2 (C.5.7) 2024-04-07 MDCK1 320 640 320 320 640 244809 B/Estonia/178996/2024 V1A.3a.2 (C.5.7) 2024-04-11 MDCK1 640 640 320 320 640 244624 B/Croatia/2798/2024 V1A.3a.2 (C.5.7) 2024-05-17 MDCK1 320 640 320 160 640 244623 B/Croatia/2825/2024 V1A.3a.2 (C.5.7) 2024-05-20 MDCK1 640 1280 640 320 1280 244578 B/HongKong/191/2024 V1A.3a.2 (C.5.7) 2024-06-15 MDCK 1/MDCK1 640 640 320 320 640 244576 B/HongKong/194/2024 V1A.3a.2 (C.5.7) 2024-06-20 MDCK 1/MDCK1 640 1280 640 640 1280
Vaccine Vaccine SH 2022 SH 2022
NH 2022-23 NH 2022-23 SH 2023 SH 2023
NH 2023-24 NH 2023-24 SH 2024 SH 2024
NH 2024-25 NH 2024-25
Table BV-13. Antigenic analyses of influenza B viruses (Victoria lineage) 2024-09-11
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
19
Summary of sample characterisation We follow a sequencing‑first approach where we sequence all the clinical samples, with further selection of samples for isolation in cell culture and antigenic characterisation based on representative genetic diversity. Samples with identical sequences may not be selected for further characterisation.
Antigenic characterisation Genetic characterisation Antiviral susceptibility phenotypic testing
Virus name Original passage sent Collection date Type/Subtype Date received HI table date HI comments
WIC Passage history
Genetic clade
Submitted to GISAID EPI Accession
Sequencing comments Oseltamivir Zanamivir
Baloxavir marboxil
B/Estonia/KL2271/2024 cs 2024‑04‑30 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406533 B/Estonia/179115/2024 cs 2024‑04‑25 BV 2024‑08‑30 Virus not recovered cs no sequence B/Estonia/KL2201/2024 cs 2024‑04‑22 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406528 B/Estonia/KL2193/2024 cs 2024‑04‑22 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406536 B/Estonia/179024/2024 cs 2024‑04‑19 BV 2024‑08‑30 Virus not recovered cs no sequence B/Estonia/KL2130/2024 cs 2024‑04‑11 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406531 B/Estonia/178996/2024 cs 2024‑04‑11 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406539 Normal inhibition Normal inhibition Normal inhibition B/Estonia/178996/2024 cs 2024‑04‑11 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440460 Normal inhibition Normal inhibition Normal inhibition B/Estonia/KL2124/2024 cs 2024‑04‑10 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406534 B/Estonia/179136/2024 cs 2024‑04‑07 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406542 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179136/2024 cs 2024‑04‑07 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440461 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179138/2024 cs 2024‑04‑05 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406537 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179138/2024 cs 2024‑04‑05 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440462 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179145/2024 cs 2024‑04‑03 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5) 2024‑09‑11 19406545 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179145/2024 cs 2024‑04‑03 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5) 2024‑09‑26 19440463 Normal inhibition Normal inhibition Normal inhibition B/Estonia/178855/2024 cs 2024‑04‑03 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406541 B/Estonia/KL2078/2024 cs 2024‑04‑02 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406548 B/Estonia/178792/2024 cs 2024‑04‑02 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406544 B/Estonia/178789/2024 cs 2024‑04‑02 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178854/2024 cs 2024‑03‑30 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5) 2024‑09‑11 19406551 B/Estonia/178854/2024 cs 2024‑03‑30 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5) 2024‑10‑08 19465941 B/Estonia/178853/2024 cs 2024‑03‑29 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/KL2050/2024 cs 2024‑03‑27 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406524 B/Estonia/KL2055/2024 cs 2024‑03‑26 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178758/2024 cs 2024‑03‑26 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178645/2024 cs 2024‑03‑20 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/KL1912/2024 cs 2024‑02‑28 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178397/2024 cs 2024‑02‑28 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178394/2024 cs 2024‑02‑28 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406523 B/Estonia/178321/2024 cs 2024‑02‑25 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178203/2024 cs 2024‑02‑13 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406527 B/Estonia/178203/2024 cs 2024‑02‑13 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.1) 2024‑10‑08 19465942 B/Estonia/KL1667/2024 cs 2024‑01‑25 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406521 B/Estonia/KL1667/2024 cs 2024‑01‑25 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.7) 2024‑10‑08 19465943 B/Estonia/177730/2024 cs 2024‑01‑24 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406525 B/Estonia/177406/2023 cs 2023‑12‑22 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406530 B/Estonia/177406/2023 cs 2023‑12‑22 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.1) 2024‑10‑08 19465944 A/Estonia/178804/2024 cs 2024‑04‑03 H1pdm 2024‑08‑30 2024‑09‑18 cs 5a.2a (C.1.8) 2024‑09‑11 19406627 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178804/2024 cs 2024‑04‑03 H1pdm 2024‑08‑30 2024‑09‑18 MDCK2 5a.2a (C.1.8) 2024‑09‑26 19440499 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178852/2024 cs 2024‑03‑28 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406638 A/Estonia/KL2045/2024 cs 2024‑03‑26 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406629 A/Estonia/179137/2024 cs 2024‑03‑11 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1.9) 2024‑09‑11 19406640 Normal inhibition Normal inhibition Normal inhibition A/Estonia/179137/2024 cs 2024‑03‑11 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1.9) 2024‑09‑26 19440451 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178398/2024 cs 2024‑02‑29 H1pdm 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177712/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1) 2024‑09‑11 19406631 Normal inhibition Normal inhibition Failed A/Estonia/177712/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1) 2024‑09‑26 19440450 Normal inhibition Normal inhibition Failed A/Estonia/177710/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406644 A/Estonia/177687/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406633 A/Estonia/177675/2024 cs 2024‑01‑20 H1pdm 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177672/2024 cs 2024‑01‑17 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406649 A/Estonia/177612/2024 cs 2024‑01‑16 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406635 A/Estonia/177563/2024 cs 2024‑01‑15 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1) 2024‑09‑11 19406777 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177563/2024 cs 2024‑01‑15 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1) 2024‑09‑26 19440449 Normal inhibition Normal inhibition Normal inhibition
20
(continued)
Antigenic characterisation Genetic characterisation Antiviral susceptibility phenotypic testing
Virus name Original passage sent Collection date Type/Subtype Date received HI table date HI comments
WIC Passage history
Genetic clade
Submitted to GISAID EPI Accession
Sequencing comments Oseltamivir Zanamivir
Baloxavir marboxil
A/Estonia/177593/2024 cs 2024‑01‑12 H1pdm 2024‑08‑30 Failed sequence – not cultured cs no sequence A/Estonia/177592/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406776 A/Estonia/177568/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 2024‑09‑24 cs 5a.2a (C.1.9) 2024‑09‑11 19406779 Normal inhibition Normal inhibition A/Estonia/177568/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 2024‑09‑24 MDCK1 5a.2a (C.1.9) 2024‑10‑08 19465925 Normal inhibition Normal inhibition A/Estonia/177534/2024 cs 2024‑01‑10 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406778 A/Estonia/177408/2024 cs 2024‑01‑02 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406519 A/Estonia/179133/2024 cs 2024‑03‑04 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409565 A/Estonia/179133/2024 cs 2024‑03‑04 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440409 A/Estonia/178187/2024 cs 2024‑02‑13 H3 2024‑08‑30 2024‑09‑10 cs no sequence A/Estonia/178187/2024 cs 2024‑02‑13 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.1) 2024‑09‑26 19440408 A/Estonia/178093/2024 cs 2024‑02‑12 H3 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/178200/2024 cs 2024‑02‑08 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409564 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178200/2024 cs 2024‑02‑08 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440411 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177999/2024 cs 2024‑02‑03 H3 2024‑08‑30 2024‑09‑19 cs 2a.3a.1 (J.2) 2024‑09‑11 19409562 Insufficient Titre Insufficient Titre A/Estonia/177999/2024 cs 2024‑02‑03 H3 2024‑08‑30 2024‑09‑19 SIAT2 2a.3a.1 (J.2) 2024‑09‑26 19440477 Insufficient Titre Insufficient Titre A/Estonia/178001/2024 cs 2024‑01‑30 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.1) 2024‑09‑11 19409563 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178001/2024 cs 2024‑01‑30 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.1) 2024‑09‑26 19440410 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177892/2024 cs 2024‑01‑26 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409561 A/Estonia/177892/2024 cs 2024‑01‑26 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440413 A/Estonia/177843/2024 cs 2024‑01‑23 H3 2024‑08‑30 Virus not recovered cs 2a.3a.1 (J.2) 2024‑09‑11 19409560 A/Estonia/177610/2024 cs 2024‑01‑15 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409559 Insufficient Titre Insufficient Titre A/Estonia/177610/2024 cs 2024‑01‑15 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440412 Insufficient Titre Insufficient Titre A/Estonia/177562/2024 cs 2024‑01‑12 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409557 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177562/2024 cs 2024‑01‑12 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440415 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177583/2024 cs 2024‑01‑10 H3 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177566/2024 cs 2024‑01‑10 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409558 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177566/2024 cs 2024‑01‑10 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440414 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177533/2024 cs 2024‑01‑09 H3 2024‑08‑30 Virus not recovered cs 2a.3a.1 (J.2) 2024‑09‑11 19409556
21
Summary of the latest WHO Influenza Vaccine Compositionmeetings Genetic and antigenic characterization data generated at the Worldwide Influenza Centre for viruses with collec‑ tion dates from 1 February 2024 until 31 August 2024 informed the WHO influenza vaccine composition meeting (VCM) in September 2024 when recommendations were made for the Southern hemisphere (SH) 2025 influenza season. At the September 2024 VCM it was recommended to change the A(H3N2) vaccine components for the 2025 SH season. Previously, at the February 2024 VCM, which focused on data from viruses collected from 1 September 2023 until 31 January 2024, it was also recommended to change the A(H3N2) vaccine components for the 2024–2025 NH season
It is recommended that vaccines for use in the 2025 SH influenza season contain the following:
Trivalent: Egg‑based Vaccines
• an A/Victoria/4897/2022 (H1N1)pdm09‑like virus;
• an A/Croatia/10136RV/2023 (H3N2)‑like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)‑like virus.
Trivalent: Cell‑ or recombinant‑based Vaccines
• an A/Wisconsin/67/2022 (H1N1)pdm09‑like virus;
• an A/District of Columbia/27/2023 (H3N2)‑like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)‑like virus.
Quadrivalent (egg‑or cell culture‑or recombinant‑basedvaccines): Above3components; andaB/Phuket/3073/2013 (B/Yamagata lineage)‑like virus.
Influenza B/Yamagata‑lineage
No B/Yamagata‑lineage viruses with collection dates after March 2020 have been reported as confirmed detection or sequences released in GISAID as of 30 September 2024.
The absence of confirmed detection of naturally occurring B/Yamagata lineage viruses is indicative of very low risk of infection by B/Yamagata lineage viruses. Therefore, it is the opinion of the WHO influenza vaccine composition advisory committee that inclusion of a B/Yamagata lineage antigen in quadrivalent influenza vaccines is no longer warranted, and every effort should be made to exclude this component as soon as possible. A continued effort by all NICs of GISRS is required to identify B/Yamagata‑lineage viruses for detailed characterization to determine if there are any in circulation.
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Seasonal viruses
Note: During the September 2022 VCM, virus genetic clade/group nomenclature for seasonal influenza viruses was reviewed by the WHO Collaborating Centres. The main text of this Technical Note employs this new nomenclature. In addition, most recent clade definitions are combined with Nextstrain / Nextclade subclade classification (shown within parentheses) which provides a more detailed resolution to describe genetic diversity. Influenza type A viruses A(H1N1)pdm09 All A(H1N1)pdm09 viruses detected recently descend from 6B.1A.5a. The new nomenclature drops the prefix 6B.1A. Clade 5a has split into two antigenically distinct clusters: Clade 5a.1 (no longer circulating, see Annex) and Clade 5a.2, represented by former vaccine virus: A/Victoria/2570/2019. Signature amino acid substitutions are described against A/Victoria/2570/2019 from here onwards.
• Clade 5a.2 o signature amino acid substitutions K130N, N156K, A187D, L161I and V250A o Vaccine virus: A/Victoria/2570/2019 o Clade 5a.2a (C.1)
o signature amino acid substitutions Clade 5a.2 + K54Q, A186T, E224A, R259K and K308R.
Vaccine virus: A/Sydney/5/2021 Clade 5a.2a (C.1.2)
• signature amino acid substitutions Clade 5a.2a (C.1) + A48P • Reference virus: A/Maine/10/2022
Clade 5a.2a (C.1.3) • signature amino acid substitutions Clade 5a.2a (C.1) + A73T, A141E,
V152I, S190I, T216A • Reference virus: A/Washington/22/2023
Clade 5a.2a (C.1.4) • signature amino acid substitutions Clade 5a.2a (C.1) + S85P, H273Q,
V321I • Reference virus: A/Maldives/936/2023
Clade 5a.2a (C.1.5) • signature amino acid substitutions Clade 5a.2a (C.1) + I185V • Reference virus: A/Bulgaria/234/2023
Clade 5a.2a (C.1.6) • signature amino acid substitutions Clade 5a.2a (C.1) with I418V +
L70I, K169R, K211Q • Reference virus: A/South Dakota/31/2023
Clade 5a.2a (C.1.7) • signature amino acid substitutions Clade 5a.2a (C.1) + I533V • Reference virus: A/Darwin/422/2023
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o Clade 5a.2a (C.1) + I418V
Reference virus: A/Netherlands/10468/2023 Clade 5a.2a (C.1.8)
• signature amino acid substitutions Clade 5a.2a (C.1) + I418V + V47I • Reference virus: A/Michigan/62/2023
Clade 5a.2a (C.1.9) • signature amino acid substitutions Clade 5a.2a (C.1) + I418V + K169Q • Reference virus: A/Lisboa/188/2023
o Clade 5a.2a.1 (C.1.1) signature amino acid substitutions Clade 5a.2a + P137S, K142R,
D260E, T277A Vaccine virus: A/Wisconsin/67/2022
o Clade 5a.2a.1 (D, former C.1.1.1) signature amino acid substitutions Clade 5a.2a.1 (C.1.1) + T216A o Vaccine virus: A/Victoria/4897/2022 Clade 5a.2a.1 (D.1)
• signature amino acid substitutions Clade 5a.2a.1 (D) + R45K • Reference virus: A/Netherlands/10481/2024
Clade 5a.2a.1 (D.2) • signature amino acid substitutions Clade 5a.2a.1 (D) + R113K,
V427I • Reference virus: A/Bretagne/05126/2024
Clade 5a.2a.1 (D.3) • signature amino acid substitutions Clade 5a.2a.1 (D) + T120A,
I372V • Reference virus: not assigned yet
Clade 5a.2a.1 (D.4) • signature amino acid substitutions Clade 5a.2a.1 (D) + T120A • Reference virus: A/Poland/28/2024
A(H3N2) All A(H3N2) viruses detected since February 2023 belong to Clade 2 (former 3C.2a1b.2a.2). Several clades and subclades emerged, of which clade 2a.3a.1 (J) predominated, with some detection of clade 2a.3a (G.1.3.1). o Clade 2a (G.1)
• Signature amino acid substitutions Clade 2 + H156S • Vaccine virus: A/Darwin/9/2021
Signature amino acid substitutions are described against A/Darwin/9/2021 from here onwards o Clade 2a.3 (G.1.3)
• Signature amino acid substitutions Clade 2a + D53N, N96S (+CHO), I192F • Reference virus: A/Norway/24873/2021 • Clade 2a.3a (G.1.3.1) Signature amino acid substitutions Clade 2a.3 + E50K Reference virus: A/Finland/402/2023 Clade 2a.3a.1 (J)
o Signature amino acid substitutions Clade 2a.3a + I140K, I223V o Vaccine virus: A/Thailand/8/2022
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o Clade 2a.3a.1 (J.1) Signature amino acid substitutions Clade 2a.3a.1 (J) + I25V, V347M
o Reference virus: A/Sydney/856/2023 Clade 2a.3a.1 (J.1.1)
• Signature amino acid substitutions Clade 2a.3a.1 (J.1) + S145N • Reference virus: A/Canberra/331/2023
o Clade 2a.3a.1 (J.2) Signature amino acid substitutions Clade 2a.3a.1 (J) + K276E Vaccine virus: A/Croatia/10136RV/2023 Clade 2a.3a.1 (J.2.1)
• Signature amino acid substitutions Clade 2a.3a.1 (J.2) + P239S • Reference virus: A/West Virginia/51/2024
Clade 2a.3a.1 (J.2.2) • Signature amino acid substitutions Clade 2a.3a.1 (J.2) + S124N • Reference virus: A/Lisboa/216/2023
o Clade 2a.3a.1 (J.3) Signature amino acid substitutions Clade 2a.3a.1 (J) + V505I Reference virus: none assigned
o Clade 2a.3a.1 (J.4) Signature amino acid substitutions Clade 2a.3a.1 (J) + Q173R, K276E Reference virus: A/France/IDF-IPP29542/2023
Influenza type B viruses B/Victoria/2/87 lineage Signature amino acid substitutions are described against B/Brisbane/60/2008. Since February 2023, all B/Victoria viruses detected globally belong to clade V1A.3a.2.
o Clade V1A.3 Signature amino acid substitutions I117V, N129D, K136E, del(162-164)
o Vaccine virus: B/Washington/02/2019 Clade V1A.3a
• Signature amino acid substitutions N150K, G184E, N197D (-CHO) and R279K • Reference virus: B/Croatia/7789/2019 • Clade V1A.3a.1
o Signature amino acid substitutions Clade V1A.3a + V220M, P241Q o Reference virus: B/Cote d’Ivoire/948/2020
• Clade V1A.3a.2 (C) o Signature amino acid substitutions Clade V1A.3a + A127T, P144L, K203R
o Vaccine virus: B/Austria/1359417/2021 • Clade V1A.3a.2 (C.2) Signature amino acid substitutions Clade V1A.3a.2 (C) +T182A, D197E,
T221A Reference virus: B/Netherlands/10335/2023
• Clade V1A.3a.2 (C.3) Signature amino acid substitutions Clade V1A.3a.2 (C) +E128K, A154E,
S208P Reference virus: B/Moldova/2030521/2023
• Clade V1A.3a.2 (C.5) Signature amino acid substitutions Clade V1A.3a.2 (C) +D197E Reference virus: B/Stockholm/3/2022
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Clade V1A.3a.2 (C.5.1) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +E183K • Reference virus: B/Catalonia/2279261NS/2023
Clade V1A.3a.2 (C.5.4) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +V117I,
E128K, A154T, K326R • Reference virus: B/Catalonia/3514402NS/2023
Clade V1A.3a.2 (C.5.6) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +D129N • Reference virus: B/Switzerland/329/2024
Clade V1A.3a.2 (C.5.7) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +E128G • Reference virus: B/Guangxi-Beiliu/2298/2023
Tähelepanu! Tegemist on väljastpoolt asutust saabunud kirjaga. Tundmatu saatja korral palume linke ja faile mitte avada.
Country Report: Estonia Worldwide Influenza Centre, WHO CC for Reference and Research on Influenza
The Francis Crick Institute, 1 Midland Road, NW1 1AT
February to August 2024
Prof. Nicola Lewis (Director ‑ WIC)
Dr. Ruth Harvey (Deputy Director)
Dr. Monica Galiano (Head of Molecular Testing and Genomics)
Dr. Alex Byrne
Dr. Zheng Xiang
Ms. Christine Carr, Ms. Burcu Ermetal
Dr. Karen Cross, Ms. Aine Rattigan
Ms. Alice Lilley, Mr. Michael Bennett
Ms. Chandrika Halai, Ms. Becky Clark, Mr. Lorin Adams
Dr. Tanya Mikaiel, Ms Abi Lofts, Dr. Alize Proust
Tel:0203 796 0563 (WIC) or [email protected]
Email: [email protected]; [email protected]; [email protected];
Formore information aboutwhatwehave observed over the last twelvemonths please see our reports for Septem‑ ber 2023 and February 2024. All of our reports since 2003 are available at https://www.crick.ac.uk/partnerships/w orldwide‑influenza‑centre/annual‑and‑interim‑reports
1
Influenza by type/subtype: Geographical distribution of seasonal influenza viruses with collection dates from February through to September 2024 as deposited in GISAID, coloured by Type/subtype. Geographic markers scaled to detection proportions.
As of September 2024, in the Northern hemisphere influenza activity in temperate countries remained at interepi‑ demic levels. Activity continued to increase in a few countries in Middle Africa.
In the Southern hemisphere, influenza activity remained elevated in some countries in South America, Eastern Africa, Southern Africa, and Oceania. Activity declined or was similar compared with the prior report across the Southern hemisphere.
The relative proportions of A/H1N1, A/H3N2 and B/Victoria varied by geographic region, with predominance of A/H3N2 in the Americas, Africa, South East Asia, Western Pacific region and Russian Federation, and some pre‑ dominance of A/H1N1 in Europe, Middle East, South Africa, Madagascar, India and Brazil. Some countries showed predominance of B/Victoria such as Canada, UK, Portugal, Syria, Ukraine, Mali, Japan and Mongolia, as indicated by the different colours in the pie charts by country.
2
Genetic diversity: Plots showing genetic diversity of A/H1N1, A/H3N2 and B/Victoria that underwent sequencing during the reporting period. A(global) B(WHO region)
3
Phylogenetic analyses: A/H1N1 6B.1A.5a.2a and 6B.1A.5a.2a.1 clade viruses both continued to circulate with differing relative proportions depending on region, with an overall predominance of 5a.2a viruses.
Globally, there is predominance of clade 5a.2a except in the Americas where there is a slight predominance of clade 5a.2a.1. In Europe, viruses from clade 5a.2a were detected with much higher frequency than clade 5a.2a.1.
Within the 5a.2a viruses, characterised by substitutions K54Q, A186T, E224A, R259K and K308R, several sub‑ clades were observed: subclade C.1 defined by substitution I418V which split into two further subclades: C.1.8, characterised by V47I with I96T in most sequences, and C.1.9, with substitution K169Q; the majority (>80%) of H1pdm viruses sequenced globally belong to subclade C.1.9, with viruses from C.1.8 as a minority subclade mostly observed in Europe. Minor subclades C.1.7 with substitution I533V and C.1.7.2 with T120A and K142R were circulating in Indonesia in low proportions.
Within the 5a.2a.1 viruses, characterised by substitutions P137S, K142R, D260E, T277A, E356D and N451H, there are twomain groups of viruses: major subcladeD (former C.1.1.1)with T216A representedby A/Victoria/4897/2022, which has split into four subclades: D.1 with R45K, D.2 with R113K and V427I, D.3 with T120A and I372V and D.4 with T120A. Of these, only subclade D circulates in significant proportions, albeit predominating only in the Americas. Subclade C.1.1 is a minor clade within 5a.2a.1 viruses with no additional substitutions represented by A/Wisconsin/67/2022, which has been detected in significant proportions only in Iceland.
All A/H1N1 viruses from Estonia belong to clade 5a.2a, of which 6 clustered within subclade 5a.2a (C.1.8), 6 within subclade 5a.2a (C.1.9) and 2 within subclade 5a.2a (C.1).
4
Global geographical distribution of influenza A/H1N1 genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade. Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of A/H1N1 viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the H1 HA gene Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
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6
Phylogenetic analyses: H3N2 Clade 3C.2a1b.2a.2 (renamed as 2) predominated since February 2023 in all geographic regions where A/H3N2 circulated.
During this reporting period, the great majority of H3 viruses detected belong to clade 2a.3a.1, which share substitution E50K with clade 2a.3a and present additional substitutions I140K and I223V (subclade J, vaccine reference A/Thailand/8/2022). Subclade J split into 4 further subclades: of these, subclade J.2 (reference A/Sydney/878/2023) characterised by N122D (‑CHO) and K276E became the dominant subclade, predominating in the majority of continents with >90% frequency. Subclade J.1 (reference A/Sydney/856/2023) characterised by I25V, V347M with additional I418V (in some viruses) was detected in minor frequencies (<10%) in Europe, South‑East Asia, Africa and Oceania. Minor subclade J.4 characterised by Q173R, K276E and some viruses with K189R predominated in West Africa earlier during the season.
Clade 2a.3a (subclade G.1.3.1, reference A/Finland/402/2023) with substitutions K276E and V347M was detected in West Africa earlier during the season.
All A/H3N2 viruses from Estonia belong to clade 2a.3a.1, of which 9 clustered within subclade 2a.3a.1 (J.2) and 2 within subclade 2a.3a.1 (J.1).
7
Global geographical distribution of influenza A/H3N2 genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade.Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of A/H3N2 viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the H3 HA gene. Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
8
9
Phylogenetic analyses:
Influenza B viruses B/Victoria lineage Clade V1A.3a.2 viruses characterised by substitutions A127T, P144L, N150K, G184E, N197D (‑CHO), K203R and R279K (B/Austria/1359417/2021, subclade C) predominated since February 2023 in geographic regions where B/Victoria‑lineage viruses were detected.
During this reporting period, only a minority of B/Victoria viruses were detected and characterised in Europe. Within V1A.3a.2, subclade C.5 with D197E represents the majority of influenza B viruses characterised during the current influenza season. The most frequent subclades observed within C.5 are: C.5.1 with E183K represented by B/Catalonia/2279261NS/2023, as the dominant subclade predominating in the Americas, Portugal, Ukraine, New Zealand and detected in several other countries in minor proportions; C.5.6 (B/Norway/08717/2023) with D129N predominating in South East Asia, Middle East, South Africa and some European countries; C.5.7 with E183K and E128G predominating in China, Japan, Australia, Russian Federation, Mongolia and some countries in Europe. Minor subclades such as C.5.4 (B/Slovenia/924/2023) with V117I, E128K, A154T and K326R were detected in Chile and the US, and C.5.5 (B/Paraguay/2102/2023) with R80G, E184K were detected in North America in very low proportions.
Outside of C.5 viruses, other subclades such as C.2 (T182A, D197E, B/Netherlands/10335/2023) and C.3 (E128K, A154E, S208P, B/Norway/5216/2023) were detected in low frequency in West Africa and Madagascar earlier during the season.
All B/Victoria viruses from Estonia belong to clade V1A.3a.2, of which 9 clustered within subclade V1A.3a.2 (C.5.7), 4 within subclade V1A.3a.2 (C.5.1), 4 within subclade V1A.3a.2 (C.5.6) and 2 within subclade V1A.3a.2 (C.5).
B/Yamagata lineage No B/Yamagata lineage viruses have been detected since March 2020.
10
Global geographical distribution of influenza B/Victoria genetic clades (subclades) viruses, obtained with full HA sequences as deposited in GISAID and classified using Nextclade.Map prepared with Microreact. Geographic markers scaled to detection proportions.
Global time‑dependent variation in frequencies of genetic clades‑subclades of B/Victoria viruses collected since 1st February 2024.
Maximum likelihood phylogenetic tree of the B/Victoria lineage HA gene Maximum likelihood phylogenetic tree inferred using Iqtree2 from HA sequence data generated at the WIC. Anno‑ tation of amino acids substitutions was performed with Treetime ancestral reconstruction. References and CVVs are marked as Cell or Egg. Virus names are colored by collection month.
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Phenotypic analyses Haemagglutination inhibition (HI) assay data: ferret antisera raised against vaccine recommendations
H1 Summary HI titres show that NH 2023‑24, 2024‑25 and SH 2024 strains, cell‑based A/Wisconsin/67/2022 and egg‑ based A/Victoria/4897/2022, generally recognised both 5a.2a and 5a.2a.1 clade viruses well. Some four‑fold drops were observed with the cell‑ based A/Wisconsin/67/2022 strain that were not seen with the egg‑based A/Victoria/4897/2022.
H3 Summary HI titres show that the SH 2024 and NH 2024‑25 vaccine strains, egg‑based A/Thailand/08/2022 (2a.3a.1 (J)) and cell‑based A/Massachusetts/18/2022 (2a.3a.1 (J)), demonstrate reduced recognition against a significant number of samples in the J.2 and J.4 subclades. The cell‑based SH 2024 and NH 2024‑25 vaccine strain, A/Massachusetts/18/2022 (2a.3a.1 (J)) recognised most viruses tested within 2‑fold, but showed significant drop in titre to some J.2 and all J.4 viruses tested to date.
Influenza B summary All V1A.3a.2 viruses tested were well recognised by antisera raised against the B/Austria/1359417/2021 vaccine virus.
Antiviral susceptibility All tested viruses were susceptible to neuraminidase inhibitors (NAI) by phenotypic testing and no geneticmarkers for reduced inhibition by NAIs were identified in NA sequences derived from clinical specimens.
Phenotypic testing for susceptibility to Baloxavir marboxil showed no reduced inhibition among all tested viruses. For all viruses where PA gene sequencing was successful, no markers associated with reduced inhibition by balox‑ avir marboxil were identified.
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HI Tables: H1
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022 A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a
(C.1.9) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1 (C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 2560 2560 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1.9) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 1280 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 1280 1280 1280 2560 640 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 1280 1280 2560 1280 1280
TEST VIRUSES 244843 A/Estonia/177563/2024 5a.2a (C.1) 2024-01-15 MDCK1 2560 2560 2560 2560 640 244837 A/Estonia/177712/2024 5a.2a (C.1) 2024-01-21 MDCK1 2560 2560 2560 2560 1280 244878 A/Luxembourg/3787860/2024 5a.2a (C.1.9) 2024-02-22 SIAT1 2560 2560 2560 2560 1280 244835 A/Estonia/179137/2024 5a.2a (C.1.9) 2024-03-11 MDCK1 2560 2560 2560 2560 1280 244596 A/HongKong/783/2024 5a.2a (C.1.9) 2024-03-12 MDCK 2/MDCK1 1280 2560 1280 1280 640 244871 A/Luxembourg/248452/2024 5a.2a (C.1.9) 2024-03-13 MDCK1 2560 1280 2560 1280 1280 244869 A/Luxembourg/5023242/2024 5a.2a (C.1.9) 2024-03-26 MDCK1 1280 2560 2560 1280 1280 244873 A/Luxembourg/3226762/2024 5a.2a.1 (C.1.1) 2024-02-02 MDCK1 2560 2560 5120 2560 2560 244630 A/Croatia/1366/2024 no sequence 2024-02-21 MDCK2 1280 1280 1280 1280 640 244628 A/Croatia/1533/2024 no sequence 2024-02-29 MDCK2 640 640 1280 640 640
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = Not Done SH 2023
SH 2024 NH 2024-25
Table H1-18. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-11)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
14
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a (C.1) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1
(C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 1280 1280 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 2560 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 1280 1280 2560 2560 1280 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 2560 2560 2560 2560 2560
TEST VIRUSES 244391 A/Spain/2606/2023 5a.2a (C.1) 2023-12-29 MDCK1 2560 2560 2560 2560 2560 244387 A/Spain/1780/2024 5a.2a (C.1) 2024-02-04 MDCK1 2560 2560 2560 1280 1280 244389 A/Spain/2201/2024 5a.2a (C.1.8) 2024-02-01 MDCK1 2560 2560 2560 2560 1280 244386 A/Spain/1814/2024 5a.2a (C.1.8) 2024-02-04 MDCK1 1280 1280 1280 1280 640 244832 A/Estonia/178804/2024 5a.2a (C.1.8) 2024-04-03 MDCK2 5120 5120 2560 2560 1280 244388 A/Spain/1810/2024 5a.2a (C.1.9) 2024-02-02 MDCK1 2560 2560 2560 2560 1280 244384 A/Spain/1720/2024 5a.2a (C.1.9) 2024-02-06 MDCK1 2560 1280 1280 1280 640 244382 A/Spain/1828/2024 5a.2a (C.1.9) 2024-02-10 MDCK1 2560 2560 2560 2560 1280 244938 A/CAT/2167458NS/2024 5a.2a (C.1.9) 2024-03-05 C1/MDCK1 5120 2560 2560 2560 2560 244937 A/CAT/3546125NS/2024 5a.2a (C.1.9) 2024-03-11 C1/MDCK1 2560 2560 2560 2560 1280 244934 A/CAT/3547217NS/2024 5a.2a (C.1.9) 2024-03-25 C1/MDCK1 2560 1280 2560 2560 1280 244383 A/Spain/1817/2024 5a.2a.1 (D) 2024-02-06 MDCK1 2560 1280 2560 1280 1280 244936 A/CAT/3546363NS/2024 5a.2a.1 (D) 2024-03-13 C1/MDCK1 2560 1280 2560 1280 2560 244935 A/CAT/2174846NS/2024 5a.2a.1 (D) 2024-03-21 C1/MDCK1 2560 1280 5120 2560 2560 244933 A/CAT/3549595NS/2024 5a.2a.1 (D) 2024-04-30 C1/MDCK1 2560 2560 5120 2560 2560 244939 A/CAT/3545504NS/2024 5a.2a.1 (D.2) 2024-03-04 C1/MDCK1 2560 2560 2560 2560 2560
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = SH 2023
SH 2024 NH 2024-25
Table H1-35. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-18)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
15
Viruses Other A/Sydney A/Lisboa/ A/Victoria/ IVR-238 A/Wisconsin/ information 5/21 188/2023 4897/2022A/Vic/4897/22 67/2022
Passage MDCK MDCK MDCK Egg MDCK
Ferret number F46/22 F09/24 F05/23 F07/23 F17/23
Genetic group Collection Date Genetic group 5a.2a
(C.1) 5a.2a (C.1) 5a.2a.1 (D) 5a.2a.1 (D) 5a.2a.1
(C.1.1)
REFERENCE VIRUSES A/Sydney/5/2021 K54Q, A186T, E224A, R259K, K308R, D94N, T216A 5a.2a (C.1) 2021-10-16 MDCK3/MDCK4 2560 1280 1280 2560 1280 A/Lisboa/188/2023 K169Q, T216A, D506E 5a.2a (C.1) 2023-11-22 SIAT1/MDCK3 2560 2560 2560 2560 2560 A/Victoria/4897/2022 P137S, K142R, T216A, D260E, T277A 5a.2a.1 (D) 2022-10-02 SIAT2/MDCK3 2560 2560 5120 2560 2560 IVR-238 (A/Victoria/4897/2022) P137S, K142R, T216A, D260E, T277A (R142K, Q223R) 5a.2a.1 (D) 2022-10-02 E3/D6/E1 2560 1280 2560 2560 1280 A/Wisconsin/67/2022 5a.2a.1 (C.1.1) 2022-10-25 MDCK2 2560 2560 2560 2560 2560
TEST VIRUSES 244846 A/Estonia/177568/2024 5a.2a (C.1.9) 2024-01-11 MDCK1 2560 2560 2560 2560 1280 244884 A/SouthSudan/1041/2024 5a.2a (C.1.9) 2024-05-29 MDCK2 5120 2560 2560 2560 1280 244882 A/SouthSudan/1023/2024 5a.2a (C.1.9) 2024-06-05 MDCK2 2560 2560 2560 2560 2560 244880 A/SouthSudan/1039/2024 5a.2a (C.1.9) 2024-06-07 MDCK1 2560 2560 2560 2560 1280
< relates to the lowest dilution of antiserum used Vaccine 1 hyperimmune sheep serum; ND = SH 2023
SH 2024 NH 2024-25
Table H1-36. Antigenic analyses of influenza A(H1N1)pdm09 viruses (2024-09-24)
Haemagglutination inhibition titre
Post-infection ferret antiserum
Vaccine NH 2023-24
16
HI Tables: H3
Viruses Other A/Albania assachusetts A/Thailand A/Sydney A/Croatia/ A/Croatia/A/Netherlands A/Slovenia A/Lisboa/A/France/IDF- A/Norway/BurkinaFaso information /289813/2022 /18/2022 /08/2022 /856/20230136/RV/20230136/RV/2023 /10563/2023 /49/2024 216/2023PP29542/2023 /12374/2023 /3131/2023
Passage SIAT SIAT Egg SIAT SIAT Egg SIAT SIAT Egg Cell Cell Cell
Ferret number F21/23 F36/23 F34/23 F01/24 F06/24 F16/24 F08/24 F11/24 F15/24 F22/24 F21/24 F32/24
COPY AND PASTE VALUES!! Genetic group Collection Date
Genetic group 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J.1) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.4) 2a.3a.1 (J.4) 2a.3a.1 (J.4)
REFERENCE VIRUSES A/Albania/289813/2022 N122D 2a.3a.1 (J) 2022-12-13MDCK1/SIAT2 1280 320 1280 640 160 160 320 80 320 160 80 40 A/Massachusetts/18/2022 2a.3a.1 (J) SIAT3/SIAT1 1280 640 1280 1280 160 160 320 80 320 320 160 80 A/Thailand/08/2022 2a.3a.1 (J) E3/E1 1280 320 1280 640 320 640 640 320 640 640 160 160 A/Sydney/856/2023 2a.3a.1 (J.1) 2023-09-12 SIAT1/SIAT2 1280 320 640 640 160 160 320 160 320 160 80 80 A/Croatia/10136/RV/2023 S145N 2a.3a.1 (J.2) 2023-12-04 SIAT3 160 80 160 160 160 160 320 320 320 320 80 40 A/Croatia/10136/RV/2023 S145N 2a.3a.1 (J.2) E3 (Am1Al2) 640 320 640 640 640 640 640 640 640 320 320 80 A/Netherlands/10563/2023 S124N 2a.3a.1 (J.2) 2023-11-10 K-MIX2/SIAT3 320 160 320 320 160 320 320 160 320 320 160 40 A/Slovenia/49/2024 N158K 2a.3a.1 (J.2) 2024-01-08MDCKx/SIAT3 40 <40 160 <40 80 40 40 1280 160 <40 40 <40 A/Lisboa/216/2023 S124N 2a.3a.1 (J.2) 2023-12-15 E3 (Am1Al2) 640 320 640 640 320 320 640 320 640 320 160 80 A/France/IDF-IPP29542/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-30MDCK1/SIAT2 <40 <40 40 40 40 80 80 <40 40 80 40 40 A/Norway/12374/2023 2a.3a.1 (J.4) 2023-11-28 SIAT4 160 80 160 160 160 160 320 80 160 160 80 80 A/BurkinaFaso/3131/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-20 SIAT3 80 40 80 <40 80 80 80 <40 80 80 80 80
TEST VIRUSES 244854 A/Estonia/178001/2024 2a.3a.1 (J.1) 2024-01-30 SIAT1 640 320 640 640 160 160 320 80 320 160 80 80 244850 A/Estonia/178187/2024 2a.3a.1 (J.1) 2024-02-13 SIAT1 640 640 640 640 160 160 320 80 320 160 80 40 244860 A/Estonia/177566/2024 2a.3a.1 (J.2) 2024-01-10 SIAT1 320 160 320 160 160 160 320 160 160 160 80 40 244858 A/Estonia/177562/2024 2a.3a.1 (J.2) 2024-01-12 SIAT1 320 80 160 160 160 160 160 80 160 160 80 40 244857 A/Estonia/177610/2024 2a.3a.1 (J.2) 2024-01-15 SIAT1 160 80 320 160 320 160 320 160 160 160 160 80 244855 A/Estonia/177892/2024 2a.3a.1 (J.2) 2024-01-26 SIAT1 320 80 320 160 160 160 320 160 320 320 80 40 244876 A/Luxembourg/6475699/2024 2a.3a.1 (J.2) 2024-02-06 SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244852 A/Estonia/178200/2024 2a.3a.1 (J.2) 2024-02-08 SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244633 A/Croatia/1613/2024 2a.3a.1 (J.2) 2024-03-04 SIAT2 160 40 160 80 80 160 160 80 160 80 40 <40 244849 A/Estonia/179133/2024 2a.3a.1 (J.2) 2024-03-04 SIAT1 320 160 320 160 320 160 320 160 320 160 160 40 244716 A/Ile_de_France/06119/2024 2a.3a.1 (J.2) 2024-05-24 C2/SIAT2 640 160 320 80 320 160 320 160 640 160 80 <40 244798 A/Bangui/172/2024 2a.3a.1 (J.2) 2024-07-11 SIAT1 640 160 640 320 320 320 320 160 320 160 160 40
SH 2024 NH 2024-25
Table H3-22. Antigenic analyses of influenza A(H3N2) viruses (Guinea Pig RBC with 20nm Oseltamivir) 2024-09-10
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
Vaccine
17
Viruses Other A/AlbaniaMassachusetts A/Thailand A/Sydney A/Croatia/ A/Croatia/A/Netherlands A/Slovenia A/Lisboa/A/France/IDF- A/Norway /BurkinaFaso information /289813/2022 /18/2022 /08/2022 /856/2023 0136/RV/2023 0136/RV/2023 /10563/2023 /49/2024 216/2023PP29542/2023 /12374/2023 /3131/2023
Passage SIAT SIAT Egg SIAT SIAT Egg SIAT SIAT Egg Cell Cell Cell
Ferret number F21/23 F36/23 F34/23 F01/24 F06/24 F16/24 F08/24 F11/24 F15/24 F22/24 F21/24 F32/24
COPY AND PASTE VALUES!! Genetic group Collection Date Genetic group 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J) 2a.3a.1 (J.1) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.2) 2a.3a.1 (J.4) 2a.3a.1 (J.4) 2a.3a.1 (J.4)
REFERENCE VIRUSES A/Albania/289813/2022 N122D 2a.3a.1 (J) 2022-12-13 MDCK1/SIAT2 1280 640 1280 1280 160 160 320 160 320 320 160 80 A/Massachusetts/18/2022 2a.3a.1 (J) SIAT3/SIAT1 1280 640 1280 1280 160 160 320 80 320 320 80 80 A/Thailand/08/2022 2a.3a.1 (J) E3/E1 1280 320 640 640 320 320 640 320 640 320 160 160 A/Sydney/856/2023 2a.3a.1 (J.1) 2023-09-12 SIAT1/SIAT2 640 320 640 640 160 160 320 80 320 160 80 80 A/Croatia/10136/RV/2023 2a.3a.1 (J.2) 2023-12-04 SIAT3 160 80 160 160 160 160 320 160 160 160 80 40 A/Croatia/10136/RV/2023 2a.3a.1 (J.2) E3 (Am1Al2) 640 160 640 640 640 640 640 320 640 640 160 80 A/Netherlands/10563/2023 2a.3a.1 (J.2) 2023-11-10 MDCK-MIX2/SIAT3 320 160 320 320 160 320 320 160 320 320 160 40 A/Slovenia/49/2024 N158K 2a.3a.1 (J.2) 2024-01-08 MDCKx/SIAT3 <40 <40 80 <40 80 40 80 1280 160 <40 40 <40 A/Lisboa/216/2023 S124N 2a.3a.1 (J.2) 2023-12-15 E3 (Am1Al2) 320 160 640 640 160 320 320 320 640 320 160 80 A/France/IDF-IPP29542/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-30 MDCK1/SIAT2 <40 <40 40 <40 40 40 40 <40 40 40 40 80 A/Norway/12374/2023 2a.3a.1 (J.4) 2023-11-28 SIAT4 160 80 160 80 80 160 320 80 160 160 80 80 A/BurkinaFaso/3131/2023 R142G, K189R 2a.3a.1 (J.4) 2023-11-20 SIAT3 40 <40 80 <40 80 40 80 <40 40 80 40 80
TEST VIRUSES 244218 A/Catalonia/NSVH102359047/2024 2a.3a.1 (J) 2024-06-07 SIAT2/MDCK1 320 160 320 320 160 160 160 80 80 80 40 <40 244875 A/Luxembourg/2651601/2024 2a.3a.1 (J.1) 2024-02-12 SIAT1 640 320 640 640 160 160 160 80 320 160 80 40 244947 A/CAT/3545207NS/2024 2a.3a.1 (J.1) 2024-02-26 C1/SIAT1 640 320 640 640 160 160 320 80 160 320 80 80 244944 A/CAT/3545572NS/2024 2a.3a.1 (J.1) 2024-03-04 C1/SIAT1 320 160 320 320 80 160 160 80 80 160 40 40 244853 A/Estonia/177999/2024 2a.3a.1 (J.2) 2024-02-03 SIAT2 320 160 320 320 160 320 320 160 320 320 160 40 244945 A/CAT/3545505NS/2024 2a.3a.1 (J.2) 2024-03-04 C1/SIAT1 320 80 320 160 160 160 320 160 320 160 80 40 244946 A/CAT/3545411NS/2024 2a.3a.1 (J.2) 2024-03-04 C1/SIAT1 320 160 320 160 160 160 320 160 320 160 80 40 244943 A/CAT/3545938NS/2024 2a.3a.1 (J.2) 2024-03-11 C1/SIAT1 320 80 160 160 160 160 320 160 320 160 80 40 244942 A/CAT/2175033NS/2024 2a.3a.1 (J.2) 2024-03-21 C1/SIAT1 320 160 320 320 160 160 320 160 320 160 80 40 244941 A/CAT/3549065NS/2024 2a.3a.1 (J.2) 2024-04-21 C1/SIAT1 320 80 320 160 160 160 320 160 160 160 80 40 244940 A/CAT/2194631NS/2024 2a.3a.1 (J.2) 2024-05-02 C1/SIAT1 160 80 320 160 160 160 320 160 320 160 80 40 244904 A/SouthSudan/1069/2024 2a.3a.1 (J.2) 2024-07-12 SIAT1 160 80 160 160 160 160 320 160 320 160 80 40 244899 A/SouthSudan/1064/2024 2a.3a.1 (J.2) 2024-07-17 SIAT1 160 80 160 160 160 160 160 160 320 160 80 40 244901 A/SouthSudan/1062/2024 2a.3a.1 (J.2) 2024-07-17 SIAT1 640 320 640 640 320 320 640 320 640 640 320 80 244887 A/SouthSudan/1045/2024 2a.3a.1 (J.2) 2024-07-29 SIAT1 160 80 160 160 160 160 320 160 320 160 80 40 244886 A/SouthSudan/1044/2024 2a.3a.1 (J.2) 2024-07-31 SIAT1 320 160 160 160 160 160 320 160 320 160 80 40
Table H3-36. Antigenic analyses of influenza A(H3N2) viruses (Guinea Pig RBC with 20nm Oseltamivir) 2024-09-19
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
Vaccine SH 2024
NH 2024-25
18
HI tables: Influenza B
Viruses Other B/Bris B/Austria B/Austria B/Austria B/Stock information 60/08 1359417/21 1359417/21 1359417/21 3/22
Passage Egg MDCK Egg G141 Egg G141R MDCK
Ferret number
Sh 539, 540, 543, 544, 570, 571, 5741
NIB F01/21 F40/21 F44/21 F28/22
COPY AND PASTE VALUES!! Genetic group Collection Date Genetic group V1A V1A.3a.2 (C) V1A.3a.2 (C) V1A.3a.2 (C) V1A.3a.2
(C.5)
REFERENCE VIRUSES B/Brisbane/60/2008 V1A 2008-08-04 E4/E3 2560 40 <40 <40 <40 B/Austria/1359417/2021 A127T, P144L, K302R (G141) V1A.3a.2 (C) 2021-01-09 SIAT1/MDCK4 640 1280 640 320 640 B/Austria/1359417/2021 A127T, P144L, K302R (G141) V1A.3a.2 (C) 2021-01-09 E3/E4 320 1280 640 320 640 B/Austria/1359417/2021 A127T, P144L, K302R (G141R) V1A.3a.2 (C) 2021-01-09 E3/E5 320 1280 640 2560 640 B/Stockholm/3/2022 D129G, E183K, D197E V1A.3a.2 (C.5) 2022-03-22 SIAT1/MDCK3 320 640 640 320 640
TEST VIRUSES 244813 B/Estonia/179145/2024 V1A.3a.2 (C.5) 2024-04-03 MDCK1 320 640 320 160 640 244580 B/HongKong/190/2024 V1A.3a.2 (C.5) 2024-06-14 MDCK 1/MDCK1 640 640 320 160 640 244574 B/HongKong/192/2024 V1A.3a.2 (C.5) 2024-06-21 MDCK 1/MDCK1 640 1280 640 320 640 244864 B/Luxembourg/3510796/2024 V1A.3a.2 (C.5.1) 2024-04-25 MDCK1 320 640 320 320 640 244622 B/Croatia/3095/2024 V1A.3a.2 (C.5.1) 2024-06-10 MDCK1 640 640 320 320 640 244625 B/Croatia/1694/2024 V1A.3a.2 (C.5.6) 2024-03-08 MDCK1 640 640 320 320 1280 244867 B/Luxembourg/9513091/2024 V1A.3a.2 (C.5.7) 2024-03-05 MDCK1 320 640 320 320 640 244812 B/Estonia/179138/2024 V1A.3a.2 (C.5.7) 2024-04-05 MDCK1 320 640 320 320 640 244811 B/Estonia/179136/2024 V1A.3a.2 (C.5.7) 2024-04-07 MDCK1 320 640 320 320 640 244809 B/Estonia/178996/2024 V1A.3a.2 (C.5.7) 2024-04-11 MDCK1 640 640 320 320 640 244624 B/Croatia/2798/2024 V1A.3a.2 (C.5.7) 2024-05-17 MDCK1 320 640 320 160 640 244623 B/Croatia/2825/2024 V1A.3a.2 (C.5.7) 2024-05-20 MDCK1 640 1280 640 320 1280 244578 B/HongKong/191/2024 V1A.3a.2 (C.5.7) 2024-06-15 MDCK 1/MDCK1 640 640 320 320 640 244576 B/HongKong/194/2024 V1A.3a.2 (C.5.7) 2024-06-20 MDCK 1/MDCK1 640 1280 640 640 1280
Vaccine Vaccine SH 2022 SH 2022
NH 2022-23 NH 2022-23 SH 2023 SH 2023
NH 2023-24 NH 2023-24 SH 2024 SH 2024
NH 2024-25 NH 2024-25
Table BV-13. Antigenic analyses of influenza B viruses (Victoria lineage) 2024-09-11
Haemagglutination inhibition titre
Post-infection ferret antiserum
< relates to the lowest dilution of antiserum used 1 hyperimmune sheep serum; ND = Not Done
19
Summary of sample characterisation We follow a sequencing‑first approach where we sequence all the clinical samples, with further selection of samples for isolation in cell culture and antigenic characterisation based on representative genetic diversity. Samples with identical sequences may not be selected for further characterisation.
Antigenic characterisation Genetic characterisation Antiviral susceptibility phenotypic testing
Virus name Original passage sent Collection date Type/Subtype Date received HI table date HI comments
WIC Passage history
Genetic clade
Submitted to GISAID EPI Accession
Sequencing comments Oseltamivir Zanamivir
Baloxavir marboxil
B/Estonia/KL2271/2024 cs 2024‑04‑30 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406533 B/Estonia/179115/2024 cs 2024‑04‑25 BV 2024‑08‑30 Virus not recovered cs no sequence B/Estonia/KL2201/2024 cs 2024‑04‑22 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406528 B/Estonia/KL2193/2024 cs 2024‑04‑22 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406536 B/Estonia/179024/2024 cs 2024‑04‑19 BV 2024‑08‑30 Virus not recovered cs no sequence B/Estonia/KL2130/2024 cs 2024‑04‑11 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406531 B/Estonia/178996/2024 cs 2024‑04‑11 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406539 Normal inhibition Normal inhibition Normal inhibition B/Estonia/178996/2024 cs 2024‑04‑11 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440460 Normal inhibition Normal inhibition Normal inhibition B/Estonia/KL2124/2024 cs 2024‑04‑10 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406534 B/Estonia/179136/2024 cs 2024‑04‑07 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406542 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179136/2024 cs 2024‑04‑07 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440461 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179138/2024 cs 2024‑04‑05 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406537 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179138/2024 cs 2024‑04‑05 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5.7) 2024‑09‑26 19440462 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179145/2024 cs 2024‑04‑03 BV 2024‑08‑30 2024‑09‑11 cs V1A.3a.2 (C.5) 2024‑09‑11 19406545 Normal inhibition Normal inhibition Normal inhibition B/Estonia/179145/2024 cs 2024‑04‑03 BV 2024‑08‑30 2024‑09‑11 MDCK1 V1A.3a.2 (C.5) 2024‑09‑26 19440463 Normal inhibition Normal inhibition Normal inhibition B/Estonia/178855/2024 cs 2024‑04‑03 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406541 B/Estonia/KL2078/2024 cs 2024‑04‑02 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406548 B/Estonia/178792/2024 cs 2024‑04‑02 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406544 B/Estonia/178789/2024 cs 2024‑04‑02 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178854/2024 cs 2024‑03‑30 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5) 2024‑09‑11 19406551 B/Estonia/178854/2024 cs 2024‑03‑30 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5) 2024‑10‑08 19465941 B/Estonia/178853/2024 cs 2024‑03‑29 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/KL2050/2024 cs 2024‑03‑27 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406524 B/Estonia/KL2055/2024 cs 2024‑03‑26 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178758/2024 cs 2024‑03‑26 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178645/2024 cs 2024‑03‑20 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/KL1912/2024 cs 2024‑02‑28 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178397/2024 cs 2024‑02‑28 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178394/2024 cs 2024‑02‑28 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406523 B/Estonia/178321/2024 cs 2024‑02‑25 BV 2024‑08‑30 Failed sequence – not cultured cs no sequence B/Estonia/178203/2024 cs 2024‑02‑13 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406527 B/Estonia/178203/2024 cs 2024‑02‑13 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.1) 2024‑10‑08 19465942 B/Estonia/KL1667/2024 cs 2024‑01‑25 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.7) 2024‑09‑11 19406521 B/Estonia/KL1667/2024 cs 2024‑01‑25 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.7) 2024‑10‑08 19465943 B/Estonia/177730/2024 cs 2024‑01‑24 BV 2024‑08‑30 Virus not recovered cs V1A.3a.2 (C.5.6) 2024‑09‑11 19406525 B/Estonia/177406/2023 cs 2023‑12‑22 BV 2024‑08‑30 2024‑09‑24 cs V1A.3a.2 (C.5.1) 2024‑09‑11 19406530 B/Estonia/177406/2023 cs 2023‑12‑22 BV 2024‑08‑30 2024‑09‑24 MDCK1 V1A.3a.2 (C.5.1) 2024‑10‑08 19465944 A/Estonia/178804/2024 cs 2024‑04‑03 H1pdm 2024‑08‑30 2024‑09‑18 cs 5a.2a (C.1.8) 2024‑09‑11 19406627 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178804/2024 cs 2024‑04‑03 H1pdm 2024‑08‑30 2024‑09‑18 MDCK2 5a.2a (C.1.8) 2024‑09‑26 19440499 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178852/2024 cs 2024‑03‑28 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406638 A/Estonia/KL2045/2024 cs 2024‑03‑26 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406629 A/Estonia/179137/2024 cs 2024‑03‑11 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1.9) 2024‑09‑11 19406640 Normal inhibition Normal inhibition Normal inhibition A/Estonia/179137/2024 cs 2024‑03‑11 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1.9) 2024‑09‑26 19440451 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178398/2024 cs 2024‑02‑29 H1pdm 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177712/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1) 2024‑09‑11 19406631 Normal inhibition Normal inhibition Failed A/Estonia/177712/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1) 2024‑09‑26 19440450 Normal inhibition Normal inhibition Failed A/Estonia/177710/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406644 A/Estonia/177687/2024 cs 2024‑01‑21 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406633 A/Estonia/177675/2024 cs 2024‑01‑20 H1pdm 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177672/2024 cs 2024‑01‑17 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406649 A/Estonia/177612/2024 cs 2024‑01‑16 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406635 A/Estonia/177563/2024 cs 2024‑01‑15 H1pdm 2024‑08‑30 2024‑09‑11 cs 5a.2a (C.1) 2024‑09‑11 19406777 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177563/2024 cs 2024‑01‑15 H1pdm 2024‑08‑30 2024‑09‑11 MDCK1 5a.2a (C.1) 2024‑09‑26 19440449 Normal inhibition Normal inhibition Normal inhibition
20
(continued)
Antigenic characterisation Genetic characterisation Antiviral susceptibility phenotypic testing
Virus name Original passage sent Collection date Type/Subtype Date received HI table date HI comments
WIC Passage history
Genetic clade
Submitted to GISAID EPI Accession
Sequencing comments Oseltamivir Zanamivir
Baloxavir marboxil
A/Estonia/177593/2024 cs 2024‑01‑12 H1pdm 2024‑08‑30 Failed sequence – not cultured cs no sequence A/Estonia/177592/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.9) 2024‑09‑11 19406776 A/Estonia/177568/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 2024‑09‑24 cs 5a.2a (C.1.9) 2024‑09‑11 19406779 Normal inhibition Normal inhibition A/Estonia/177568/2024 cs 2024‑01‑11 H1pdm 2024‑08‑30 2024‑09‑24 MDCK1 5a.2a (C.1.9) 2024‑10‑08 19465925 Normal inhibition Normal inhibition A/Estonia/177534/2024 cs 2024‑01‑10 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406778 A/Estonia/177408/2024 cs 2024‑01‑02 H1pdm 2024‑08‑30 Virus not recovered cs 5a.2a (C.1.8) 2024‑09‑11 19406519 A/Estonia/179133/2024 cs 2024‑03‑04 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409565 A/Estonia/179133/2024 cs 2024‑03‑04 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440409 A/Estonia/178187/2024 cs 2024‑02‑13 H3 2024‑08‑30 2024‑09‑10 cs no sequence A/Estonia/178187/2024 cs 2024‑02‑13 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.1) 2024‑09‑26 19440408 A/Estonia/178093/2024 cs 2024‑02‑12 H3 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/178200/2024 cs 2024‑02‑08 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409564 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178200/2024 cs 2024‑02‑08 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440411 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177999/2024 cs 2024‑02‑03 H3 2024‑08‑30 2024‑09‑19 cs 2a.3a.1 (J.2) 2024‑09‑11 19409562 Insufficient Titre Insufficient Titre A/Estonia/177999/2024 cs 2024‑02‑03 H3 2024‑08‑30 2024‑09‑19 SIAT2 2a.3a.1 (J.2) 2024‑09‑26 19440477 Insufficient Titre Insufficient Titre A/Estonia/178001/2024 cs 2024‑01‑30 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.1) 2024‑09‑11 19409563 Normal inhibition Normal inhibition Normal inhibition A/Estonia/178001/2024 cs 2024‑01‑30 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.1) 2024‑09‑26 19440410 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177892/2024 cs 2024‑01‑26 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409561 A/Estonia/177892/2024 cs 2024‑01‑26 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440413 A/Estonia/177843/2024 cs 2024‑01‑23 H3 2024‑08‑30 Virus not recovered cs 2a.3a.1 (J.2) 2024‑09‑11 19409560 A/Estonia/177610/2024 cs 2024‑01‑15 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409559 Insufficient Titre Insufficient Titre A/Estonia/177610/2024 cs 2024‑01‑15 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440412 Insufficient Titre Insufficient Titre A/Estonia/177562/2024 cs 2024‑01‑12 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409557 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177562/2024 cs 2024‑01‑12 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440415 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177583/2024 cs 2024‑01‑10 H3 2024‑08‑30 Virus not recovered cs no sequence A/Estonia/177566/2024 cs 2024‑01‑10 H3 2024‑08‑30 2024‑09‑10 cs 2a.3a.1 (J.2) 2024‑09‑11 19409558 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177566/2024 cs 2024‑01‑10 H3 2024‑08‑30 2024‑09‑10 SIAT1 2a.3a.1 (J.2) 2024‑09‑26 19440414 Normal inhibition Normal inhibition Normal inhibition A/Estonia/177533/2024 cs 2024‑01‑09 H3 2024‑08‑30 Virus not recovered cs 2a.3a.1 (J.2) 2024‑09‑11 19409556
21
Summary of the latest WHO Influenza Vaccine Compositionmeetings Genetic and antigenic characterization data generated at the Worldwide Influenza Centre for viruses with collec‑ tion dates from 1 February 2024 until 31 August 2024 informed the WHO influenza vaccine composition meeting (VCM) in September 2024 when recommendations were made for the Southern hemisphere (SH) 2025 influenza season. At the September 2024 VCM it was recommended to change the A(H3N2) vaccine components for the 2025 SH season. Previously, at the February 2024 VCM, which focused on data from viruses collected from 1 September 2023 until 31 January 2024, it was also recommended to change the A(H3N2) vaccine components for the 2024–2025 NH season
It is recommended that vaccines for use in the 2025 SH influenza season contain the following:
Trivalent: Egg‑based Vaccines
• an A/Victoria/4897/2022 (H1N1)pdm09‑like virus;
• an A/Croatia/10136RV/2023 (H3N2)‑like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)‑like virus.
Trivalent: Cell‑ or recombinant‑based Vaccines
• an A/Wisconsin/67/2022 (H1N1)pdm09‑like virus;
• an A/District of Columbia/27/2023 (H3N2)‑like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)‑like virus.
Quadrivalent (egg‑or cell culture‑or recombinant‑basedvaccines): Above3components; andaB/Phuket/3073/2013 (B/Yamagata lineage)‑like virus.
Influenza B/Yamagata‑lineage
No B/Yamagata‑lineage viruses with collection dates after March 2020 have been reported as confirmed detection or sequences released in GISAID as of 30 September 2024.
The absence of confirmed detection of naturally occurring B/Yamagata lineage viruses is indicative of very low risk of infection by B/Yamagata lineage viruses. Therefore, it is the opinion of the WHO influenza vaccine composition advisory committee that inclusion of a B/Yamagata lineage antigen in quadrivalent influenza vaccines is no longer warranted, and every effort should be made to exclude this component as soon as possible. A continued effort by all NICs of GISRS is required to identify B/Yamagata‑lineage viruses for detailed characterization to determine if there are any in circulation.
22
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Seasonal viruses
Note: During the September 2022 VCM, virus genetic clade/group nomenclature for seasonal influenza viruses was reviewed by the WHO Collaborating Centres. The main text of this Technical Note employs this new nomenclature. In addition, most recent clade definitions are combined with Nextstrain / Nextclade subclade classification (shown within parentheses) which provides a more detailed resolution to describe genetic diversity. Influenza type A viruses A(H1N1)pdm09 All A(H1N1)pdm09 viruses detected recently descend from 6B.1A.5a. The new nomenclature drops the prefix 6B.1A. Clade 5a has split into two antigenically distinct clusters: Clade 5a.1 (no longer circulating, see Annex) and Clade 5a.2, represented by former vaccine virus: A/Victoria/2570/2019. Signature amino acid substitutions are described against A/Victoria/2570/2019 from here onwards.
• Clade 5a.2 o signature amino acid substitutions K130N, N156K, A187D, L161I and V250A o Vaccine virus: A/Victoria/2570/2019 o Clade 5a.2a (C.1)
o signature amino acid substitutions Clade 5a.2 + K54Q, A186T, E224A, R259K and K308R.
Vaccine virus: A/Sydney/5/2021 Clade 5a.2a (C.1.2)
• signature amino acid substitutions Clade 5a.2a (C.1) + A48P • Reference virus: A/Maine/10/2022
Clade 5a.2a (C.1.3) • signature amino acid substitutions Clade 5a.2a (C.1) + A73T, A141E,
V152I, S190I, T216A • Reference virus: A/Washington/22/2023
Clade 5a.2a (C.1.4) • signature amino acid substitutions Clade 5a.2a (C.1) + S85P, H273Q,
V321I • Reference virus: A/Maldives/936/2023
Clade 5a.2a (C.1.5) • signature amino acid substitutions Clade 5a.2a (C.1) + I185V • Reference virus: A/Bulgaria/234/2023
Clade 5a.2a (C.1.6) • signature amino acid substitutions Clade 5a.2a (C.1) with I418V +
L70I, K169R, K211Q • Reference virus: A/South Dakota/31/2023
Clade 5a.2a (C.1.7) • signature amino acid substitutions Clade 5a.2a (C.1) + I533V • Reference virus: A/Darwin/422/2023
Page 2 of 4
o Clade 5a.2a (C.1) + I418V
Reference virus: A/Netherlands/10468/2023 Clade 5a.2a (C.1.8)
• signature amino acid substitutions Clade 5a.2a (C.1) + I418V + V47I • Reference virus: A/Michigan/62/2023
Clade 5a.2a (C.1.9) • signature amino acid substitutions Clade 5a.2a (C.1) + I418V + K169Q • Reference virus: A/Lisboa/188/2023
o Clade 5a.2a.1 (C.1.1) signature amino acid substitutions Clade 5a.2a + P137S, K142R,
D260E, T277A Vaccine virus: A/Wisconsin/67/2022
o Clade 5a.2a.1 (D, former C.1.1.1) signature amino acid substitutions Clade 5a.2a.1 (C.1.1) + T216A o Vaccine virus: A/Victoria/4897/2022 Clade 5a.2a.1 (D.1)
• signature amino acid substitutions Clade 5a.2a.1 (D) + R45K • Reference virus: A/Netherlands/10481/2024
Clade 5a.2a.1 (D.2) • signature amino acid substitutions Clade 5a.2a.1 (D) + R113K,
V427I • Reference virus: A/Bretagne/05126/2024
Clade 5a.2a.1 (D.3) • signature amino acid substitutions Clade 5a.2a.1 (D) + T120A,
I372V • Reference virus: not assigned yet
Clade 5a.2a.1 (D.4) • signature amino acid substitutions Clade 5a.2a.1 (D) + T120A • Reference virus: A/Poland/28/2024
A(H3N2) All A(H3N2) viruses detected since February 2023 belong to Clade 2 (former 3C.2a1b.2a.2). Several clades and subclades emerged, of which clade 2a.3a.1 (J) predominated, with some detection of clade 2a.3a (G.1.3.1). o Clade 2a (G.1)
• Signature amino acid substitutions Clade 2 + H156S • Vaccine virus: A/Darwin/9/2021
Signature amino acid substitutions are described against A/Darwin/9/2021 from here onwards o Clade 2a.3 (G.1.3)
• Signature amino acid substitutions Clade 2a + D53N, N96S (+CHO), I192F • Reference virus: A/Norway/24873/2021 • Clade 2a.3a (G.1.3.1) Signature amino acid substitutions Clade 2a.3 + E50K Reference virus: A/Finland/402/2023 Clade 2a.3a.1 (J)
o Signature amino acid substitutions Clade 2a.3a + I140K, I223V o Vaccine virus: A/Thailand/8/2022
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o Clade 2a.3a.1 (J.1) Signature amino acid substitutions Clade 2a.3a.1 (J) + I25V, V347M
o Reference virus: A/Sydney/856/2023 Clade 2a.3a.1 (J.1.1)
• Signature amino acid substitutions Clade 2a.3a.1 (J.1) + S145N • Reference virus: A/Canberra/331/2023
o Clade 2a.3a.1 (J.2) Signature amino acid substitutions Clade 2a.3a.1 (J) + K276E Vaccine virus: A/Croatia/10136RV/2023 Clade 2a.3a.1 (J.2.1)
• Signature amino acid substitutions Clade 2a.3a.1 (J.2) + P239S • Reference virus: A/West Virginia/51/2024
Clade 2a.3a.1 (J.2.2) • Signature amino acid substitutions Clade 2a.3a.1 (J.2) + S124N • Reference virus: A/Lisboa/216/2023
o Clade 2a.3a.1 (J.3) Signature amino acid substitutions Clade 2a.3a.1 (J) + V505I Reference virus: none assigned
o Clade 2a.3a.1 (J.4) Signature amino acid substitutions Clade 2a.3a.1 (J) + Q173R, K276E Reference virus: A/France/IDF-IPP29542/2023
Influenza type B viruses B/Victoria/2/87 lineage Signature amino acid substitutions are described against B/Brisbane/60/2008. Since February 2023, all B/Victoria viruses detected globally belong to clade V1A.3a.2.
o Clade V1A.3 Signature amino acid substitutions I117V, N129D, K136E, del(162-164)
o Vaccine virus: B/Washington/02/2019 Clade V1A.3a
• Signature amino acid substitutions N150K, G184E, N197D (-CHO) and R279K • Reference virus: B/Croatia/7789/2019 • Clade V1A.3a.1
o Signature amino acid substitutions Clade V1A.3a + V220M, P241Q o Reference virus: B/Cote d’Ivoire/948/2020
• Clade V1A.3a.2 (C) o Signature amino acid substitutions Clade V1A.3a + A127T, P144L, K203R
o Vaccine virus: B/Austria/1359417/2021 • Clade V1A.3a.2 (C.2) Signature amino acid substitutions Clade V1A.3a.2 (C) +T182A, D197E,
T221A Reference virus: B/Netherlands/10335/2023
• Clade V1A.3a.2 (C.3) Signature amino acid substitutions Clade V1A.3a.2 (C) +E128K, A154E,
S208P Reference virus: B/Moldova/2030521/2023
• Clade V1A.3a.2 (C.5) Signature amino acid substitutions Clade V1A.3a.2 (C) +D197E Reference virus: B/Stockholm/3/2022
Page 4 of 4
Clade V1A.3a.2 (C.5.1) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +E183K • Reference virus: B/Catalonia/2279261NS/2023
Clade V1A.3a.2 (C.5.4) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +V117I,
E128K, A154T, K326R • Reference virus: B/Catalonia/3514402NS/2023
Clade V1A.3a.2 (C.5.6) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +D129N • Reference virus: B/Switzerland/329/2024
Clade V1A.3a.2 (C.5.7) • Signature amino acid substitutions Clade V1A.3a.2 (C.5) +E128G • Reference virus: B/Guangxi-Beiliu/2298/2023