Fig. 4: Leading and trailing geographic regions of A/H3N2 antigenic evolution under the even sub-sampling scheme. | Nature Communications

Fig. 4: Leading and trailing geographic regions of A/H3N2 antigenic evolution under the even sub-sampling scheme.

From: Disruption of seasonal influenza circulation and evolution during the 2009 H1N1 and COVID-19 pandemics in Southeastern Asia

Fig. 4: Leading and trailing geographic regions of A/H3N2 antigenic evolution under the even sub-sampling scheme.

a Sequence-based antigenic distance from A/Wisconsin/67/2005 of all A/H3N2 virus strains plotted against time of collection. The thick grey line is the fitted line using a linear model. Points to the right of the line are antigenically advanced, whereas strains to the left of the line are antigenically lagging. Light and dark red shading denotes the A/H1N1 and COVID-19 pandemic seasons, respectively. b Antigenic distance to the fitted line by region and period. Grey oblique squares indicate the average antigenic distance to the fitted line for strains isolated in each region. Coloured circles split this overall average by various periods (2009 H1N1 pandemic, interpandemic, and COVID-19 pandemic seasons). Size of circles refers to the number of sequences that are used for the estimate. Points to the right of the graph are antigenically advanced, whereas strains to the left are antigenically lagging. Antigenic distance can also be interpreted as time using the slope of the regression line in panel a; thus, time is shown as a second x-axis (top). The absence of observations in certain periods is attributed to incomplete gene sequences, making it challenging to compute antigenic distance. PL persistent lineages, NPL non-persistent lineages.

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