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

In cases reported outside mainland China, we estimate an overall modal CFR of 2.7% (95% crI 1.4%-4.7%) using the parametric model (Table 2 ). However, this reflects a balance of cases detected in different ways in the surveillance system. In those that reported travel to mainland China (and hence will have been detected in the surveillance system due to this travel link), we estimate an overall modal CFR of 1.2% (95% crI 0.4%-4.0%). In those without any reported travel to China (therefore detected either through contact tracing or through hospital surveillance) we estimate a slightly higher CFR (although with high overlap in posterior distributions) of 3.6% (95% crI 1.9%-7.2%) using the parametric model. We estimate a lower CFR in those aged under 60 years of age (1.3%, 95% credible interval, crI 0.5%-3.5%) compared to those aged 60 years and over (4.1%, 95% crI 1.8%-11.0%) in this population. Similar estimates were obtained using non-parametric methods (Table 2) . Comparing those under and over-60 years of age, we find estimates that are consistent with those observed in cases from mainland China (Tables 1 and 2) .