a, Estimates of the infected population proportion for each country as of 1 September 2020. The y axis in a has been capped at 1, whereas in Supplementary Fig. 4 the same graph is shown with the full range of values. Grey dots indicate the median estimates by fitting the model to each individual seroprevalence survey. Coloured dots and lines represent the median and 95% credible intervals estimated by the ensemble model. b, Proportion of the population who are seropositive over time for each of the 12 countries fit with national-level seroprevalence data. Green curves and ribbons indicate the median and 95% credible intervals estimated by the ensemble model. Dots and lines represent the mean and 95% binomial confidence interval of the published seroprevalence data. For countries with more than 1 seroprevalence survey, black dots and lines correspond to the study that is designated ‘country, 1’ (for example, Sweden, 1) in Fig. 2 and Supplementary Table 1, whereas pink dots and lines correspond to the study designated ‘country, 2’ (for example, Belgium, 2) and navy dots and lines to the study designated ‘country, 3’ (for example, The Netherlands, 3). Blue-shaded regions indicate the start and end dates of sampling for each seroprevalence survey. Grey dashed lines and ribbons represent the median and 95% credible interval model estimates derived from separately fitting the model to each individual seroprevalence study.