Fig. 7.

Model fitting to first wave of the SARS-CoV-2 pandemic assuming$T_2\to \infty$. Modelled trajectories of COVID-19 deaths (black) and cumulative percentage infected (blue). Green dots are data for daily reported deaths. Basic reproduction numbers under control (${\mathcal{R}}_{\mathrm{c}}$) displayed in shallow panels underneath the main plots. Government stringency indices (Hale et al., 2020) traced in blue. Input parameters: progression from $\mathsf{E}$ to $\mathsf{I}$ ($\delta =1/5.5$ per day); recovery ($\gamma =1/4$ per day); relative infectiousness between $\mathsf{E}$ and $\mathsf{I}$ stages ($\rho =0.5$); and IFR ($\varphi =0.9\%$). Initial basic reproduction numbers, coefficients of variation and control parameters estimated by Bayesian inference (estimates in Table 2). Fitted curves represent best fitting trajectories and shades are 95% credible intervals generated from $10,000$ posterior samples. (a) Individual variation in susceptibility to infection (model (9)-(12)). (b) Individual variation in exposure to infection (17)-(20). (c) Homogeneous susceptibility and exposure (either model with $\nu =0$).