1 Institute for Immunization and Prevention, Beijing Preventive Medicine Research Center, Beijing Center for Disease Prevention and Control, 100013, Beijing, China.
2 Xicheng District Center for Disease Prevention and Control, 100120, Beijing, China.
3 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206, Beijing, China.
4 Institute for Immunization and Prevention, Beijing Preventive Medicine Research Center, Beijing Center for Disease Prevention and Control, 100013, Beijing, China. Electronic address: lulibj@sina.com.
5 Institute for Immunization and Prevention, Beijing Preventive Medicine Research Center, Beijing Center for Disease Prevention and Control, 100013, Beijing, China. Electronic address: wj81732@hotmail.com.