Fudan University - Department of Epidemiology, Chinese Center for Disease Control and Prevention (China CDC) - Shanghai Municipal Center for Disease Control and Prevention, affiliation not provided to SSRN, Chinese Center for Disease Control and Prevention (China CDC) - Shanghai Municipal Center for Disease Control and Prevention, Fudan University - Department of Biostatics, Chinese Center for Disease Control and Prevention (China CDC) - Shanghai Municipal Center for Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC) - Shanghai Municipal Center for Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC) - Shanghai Municipal Center for Disease Control and Prevention and Fudan University - Shanghai Institute of Infectious Disease and Biosecurity