Tweet
Open Forum Infect Dis
. 2023 Nov 16;10(12):ofad577.
doi: 10.1093/ofid/ofad577. eCollection 2023 Dec. Evolution of Influenza A(H3N2) Viruses in 2 Consecutive Seasons of Genomic Surveillance, 2021-2023
Amary Fall 1 , Lijie Han 1 , Madeline Yunker 1 , Yu-Nong Gong 2 3 4 5 , Tai-Jung Li 2 3 , Julie M Norton 1 , Omar Abdullah 1 , Richard E Rothman 6 , Katherine Z J Fenstermacher 6 , C Paul Morris 1 7 , Andrew Pekosz 6 8 , Eili Klein 6 9 , Heba H Mostafa 1
Affiliations
Background: The circulation and the genomic evolution of influenza A(H3N2) viruses during the 2021/2022 and 2022/2023 seasons were studied and associated with infection outcomes.
Methods: Remnant influenza A-positive samples following standard-of-care testing from patients across the Johns Hopkins Health System (JHHS) were used for the study. Samples were randomly selected for whole viral genome sequencing. The sequence-based pEpitope model was used to estimate the predicted vaccine efficacy (pVE) for circulating H3N2 viruses. Clinical data were collected and associated with viral genomic data.
Results: A total of 121 683 respiratory specimens were tested for influenza at JHHS between 1 September 2021 and 31 December 2022. Among them, 6071 (4.99%) tested positive for influenza A. Of these, 805 samples were randomly selected for sequencing, with hemagglutinin (HA) segments characterized for 610 samples. Among the characterized samples, 581 were H3N2 (95.2%). Phylogenetic analysis of HA segments revealed the exclusive circulation of H3N2 viruses with HA segments of the 3C.2a1b.2a.2 clade. Analysis of a total of 445 complete H3N2 genomes revealed reassortments; 200 of 227 of the 2022/2023 season genomes (88.1%) were found to have reassorted with clade 3C.2a1b.1a. The pVE was estimated to be -42.53% for the 2021/2022 season and 30.27% for the 2022/2023 season. No differences in clinical presentations or admissions were observed between the 2 seasons.
Conclusions: The increased numbers of cases and genomic diversity of influenza A(H3N2) during the 2022/2023 season were not associated with a change in disease severity compared to the previous influenza season.
Keywords: H3N2; influenza; reassortment; vaccine.
. 2023 Nov 16;10(12):ofad577.
doi: 10.1093/ofid/ofad577. eCollection 2023 Dec. Evolution of Influenza A(H3N2) Viruses in 2 Consecutive Seasons of Genomic Surveillance, 2021-2023
Amary Fall 1 , Lijie Han 1 , Madeline Yunker 1 , Yu-Nong Gong 2 3 4 5 , Tai-Jung Li 2 3 , Julie M Norton 1 , Omar Abdullah 1 , Richard E Rothman 6 , Katherine Z J Fenstermacher 6 , C Paul Morris 1 7 , Andrew Pekosz 6 8 , Eili Klein 6 9 , Heba H Mostafa 1
Affiliations
- PMID: 38088981
- PMCID: PMC10715682
- DOI: 10.1093/ofid/ofad577
Background: The circulation and the genomic evolution of influenza A(H3N2) viruses during the 2021/2022 and 2022/2023 seasons were studied and associated with infection outcomes.
Methods: Remnant influenza A-positive samples following standard-of-care testing from patients across the Johns Hopkins Health System (JHHS) were used for the study. Samples were randomly selected for whole viral genome sequencing. The sequence-based pEpitope model was used to estimate the predicted vaccine efficacy (pVE) for circulating H3N2 viruses. Clinical data were collected and associated with viral genomic data.
Results: A total of 121 683 respiratory specimens were tested for influenza at JHHS between 1 September 2021 and 31 December 2022. Among them, 6071 (4.99%) tested positive for influenza A. Of these, 805 samples were randomly selected for sequencing, with hemagglutinin (HA) segments characterized for 610 samples. Among the characterized samples, 581 were H3N2 (95.2%). Phylogenetic analysis of HA segments revealed the exclusive circulation of H3N2 viruses with HA segments of the 3C.2a1b.2a.2 clade. Analysis of a total of 445 complete H3N2 genomes revealed reassortments; 200 of 227 of the 2022/2023 season genomes (88.1%) were found to have reassorted with clade 3C.2a1b.1a. The pVE was estimated to be -42.53% for the 2021/2022 season and 30.27% for the 2022/2023 season. No differences in clinical presentations or admissions were observed between the 2 seasons.
Conclusions: The increased numbers of cases and genomic diversity of influenza A(H3N2) during the 2022/2023 season were not associated with a change in disease severity compared to the previous influenza season.
Keywords: H3N2; influenza; reassortment; vaccine.