Fast spread of COVID-19 in Europe and the US and its implications: even modest public health goals require comprehensive intervention

Ruian Ke; Steven Sanche; Ethan Romero-Severson; Nicholas Hengartner

Introduction 55 COVID-19 originated in Wuhan China in Dec, 2019 1 . It has spread rapidly and caused a global 56 pandemic within a short period of time. As of March 31, 2020, the global pandemic lead to more 57 than 800,000 total confirmed cases and 40,000 deaths. Estimation of the rate of early epidemic 58 spread in Wuhan, China, lead to different conclusions. Initially, it was suggested that the 59 epidemic grew at 0·1-0·14/day, leading to an epidemic doubling time of 5-7 days 2-5 . However, 60 using domestic travel data and two distinct approaches, we estimated that the epidemic in Wuhan 61 grew much faster than initially estimated, and the growth rate is likely to be between 0·21-62 0·3/day, translating to a doubling time between 2·3 to 3·3 days, and an R0 approximately at 5·7 63 with a large confidence interval 6 . A fast epidemic spread is consistent with multiple other lines of 64 evidence, such as the rapid increase of the epidemic curve by symptom onset published by China 65 CDC 7 and the growth in the number of death cases in Hubei, China during late January 2020 6 . 66