Fig. 4.

SARS-CoV-2 transmission in England and Scotland with individual variation in exposure to infection. Connectivity factors implemented as gamma distributions (reduced model (17)-(20)). Modelled trajectories of COVID-19 deaths (black) and cumulative percentage infected (blue). Dots are data for daily reported deaths: fitted (green); out-of-sample (red). Basic reproduction numbers under control (${\mathcal{R}}_{\mathrm{c}}$) displayed in shallow panels underneath the main plots. Left panels represent fitted segments as solid curves and projected scenarios as dashed. Right panels prolong those projections further in time assuming ${\mathcal{R}}_{\mathrm{c}}(t)={\mathcal{R}}_0$. 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 1). Fitted curves represent best fitting trajectories and shades are 95% credible intervals generated from $10,000$ posterior samples.