Fig. 3: SARS-CoV-2 dynamics of the mitigated and counterfactual unmitigated epidemic in Vo’ and the relative final size estimates.

a, The prevalence of SARS-CoV-2 infection inferred from the observed prevalence data for symptomatic, presymptomatic and asymptomatic infections in the first and second surveys using \({R}_{0}^{1}\) (the reproduction number before the lockdown) = 2.4 and 1/σ (the average duration of positivity beyond the duration of the infectious period) = 4 days. The dashed vertical line represents the time that the lockdown started. The points represent the observed prevalence data, the 95% CI is the exact binomial CI. The solid lines represent the mean and the shading represents the 95% credible interval obtained with the model from 100 samples from the posterior distribution of the parameters. b, The incidence of the epidemic fitted to the prevalence data (blue) and of the unmitigated epidemic (red), obtained assuming the same initial reproduction number value \({R}_{0}^{1}\) = 2.4 throughout the whole epidemic and 1/σ = 4 days. The dashed vertical line represents the time that the lockdown started. The solid lines represent the mean and the shading represents the 95% credible interval obtained with the model from 100 samples from the posterior distribution of the parameters. c, The mean epidemic final size (the proportion of the population infected at the end of the epidemic) of the counterfactual unmitigated epidemic (red) and of the epidemic fitted from the prevalence data with the lockdown (blue). The error bars represent the range (minimum to maximum) of the mean final size obtained from n = 100 independent samples drawn from the posterior distribution of the parameters, calculated over the models with DIC (deviance information criterion) < 36.4.