Data sources
Data were collected from the daily epidemic reports released by Chinese national and provincial health commissions, including numbers of confirmed, suspected and recovered cases and death toll, etc. (http://www.nhc.gov.cn/xcs/yqtb/list_gzbd.shtml). The definition of confirmed case and severe pneumonia is based on the diagnosis and treatment scheme released by the National Health Commission of China. Interested data were collected from January 21 to March 26 (reported on March 27), 2020 in 34 provinces of China including: 1) new, daily and cumulative confirmed cases; 2) new and cumulative death cases; 3) new and cumulative recovered cases; 4) daily severe pneumonia. Outside China, data were collected from daily situation reports by World Health Organization including cumulative confirmed and death cases (https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports/).