Estimates of the severity of COVID-19 disease

Robert Verity; Lucy C Okell; Ilaria Dorigatti; Peter Winskill; Charles Whittaker; Natsuko Imai; Gina Cuomo-Dannenburg; Hayley Thompson; Patrick Walker; Han Fu; Amy Dighe; Jamie Griffin; Anne Cori; Marc Baguelin; Sangeeta Bhatia; Adhiratha Boonyasiri; Zulma M Cucunuba; Rich Fitzjohn; Katy A M Gaythorpe; Will Green; Arran Hamlet; Wes Hinsley; Daniel Laydon; Gemma Nedjati-Gilani; Steven Riley; Sabine van-Elsand; Erik Volz; Haowei Wang; Yuanrong Wang; Xiayoue Xi; Christl Donnelly; Azra Ghani; Neil Ferguson

All analyses were performed using R software (version 3.6.2) with Bayesian Marko-Chain Monte Carlo (MCMC) fitting using the package drjacoby 26 . Data and code are available on https://github.com/mrcide/COVID19_CFR_submission. Figure 2A shows the subset of 24 deaths from COVID-19 that occurred in mainland China early in the epidemic. During a growing epidemic, we are more likely to observe shorter times from onset-todeath because those that occur later will not yet have been reported. Correcting for this bias, we estimate the mean time from onset-to-death to be 18.8 days (95% credible interval, crI 15.7-49.7 days) with a coefficient of variation, CV, of 0.45 days (95% crI 0.29-0.54 days). With the limited number of observations in these data and given that they were from early in the epidemic, we could not exclude many deaths occurring with longer times from onset-to-death (hence the high upper credible interval). However, given that the epidemic in China has since declined, our posterior estimate of the mean time from onset-to-death informed by the analysis of aggregated China data is more precise (mean 17.8 days, 95% crI 16.9-19.2 days, Figure 2 ).