1. From the Department of Epidemiology and Health Statistics (P.H., H.X., W.M.) and Department of Maternal and Child Health (B.X.), School of Public Health, Shandong University, Jinan, China; Independent Consultant, New York, NY (K.H.R.); and National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China (Y.W.).