Linking key intervention timings to rapid decline of the COVID-19 effective reproductive number to quantify lessons from mainland China

Xiao, Yanni; Tang, Biao; Wu, Jianhong; Cheke, Robert A.; Tang, Sanyi

Abstract Effective reproductive numbers (Rt) were calculated from data on the COVID-19 outbreak in China and linked to dates in 2020 when different interventions were enacted. From a maximum of 3.98 before the lockdown of Wuhan City, the values of Rt declined to below 1 by the second week of February, after construction of hospitals dedicated to COVID-19 patients. The Rt continued to decline following additional measures in line with the policy of “early detection, early report, early quarantine and early treatment”. The results provide quantitative evaluations of how intervention measures succeeded and their timings, from which lessons can be learnt by other countries and those dealing with future outbreaks.