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Fig. 3 | Virology Journal

Fig. 3

From: Antigenic drift and immunity gap explain reduction in protective responses against influenza A(H1N1)pdm09 and A(H3N2) viruses during the COVID-19 pandemic: a cross-sectional study of human sera collected in 2019, 2021, 2022, and 2023

Fig. 3

HAI titers against H1N1pdm09 A/Victoria/2570/2019 in sera from 2021 and 2022 in different age groups. A Reverse cumulative plots were generated from the HAI titers against A/Victoria/2570/19 from 2021 and 2022 for the age groups 0–4 years, 5–14 years, 15–24 years, 25–59 years and 60 + years. The dotted line indicates 50% protective HAI titer of 40. B Number of detected influenza A infections per 100.000 individuals in the different age groups for the period week 40 2022 to week 22 2023. C Vaccine coverage in the general population obtained from the Norwegian Immunization Registry SYSVAK for the different age groups. D Reverse cumulative plots of HAI titers in a panel of 119 sera collected in 2021 and first tested against A/Victoria/2570/2019 in 2021 and repeat tested in 2022 to verify reproducibility. A Significant differences were calculated by a two-tailed Mann–Whitney test. **p < 0.01, ***p < 0.001 and****p < 0.0001, ns = no significant difference

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Virology Journal

ISSN: 1743-422X