Department of Expanded Program Immunization;
Tianjin Center for Diseases Control and Prevention;
Tianjin 300011;
China;
National Institute for Viral Disease Control and Prevention;
Chinese Center for Diseases Control and Prevention;
Beijing 102206;
China;
Department of Viral Laboratory;
Tianjin Center for Diseases Control and Prevention;
Tiannin 300011;
China;
Institute for Infectious Diseases Control and Prevention;
Tianjin Center for Diseases Control and Prevention;
Tianjin 300011;
China;
Measles; IgG avidity; China; Primary vaccine failures; Secondary vaccine failures;