1. Department of Communicable Diseases Control and Prevention, Zhejiang Provincial Centre for Disease Control and Prevention, Hangzhou, China
2. Jiaxing Centre for Disease Control and Prevention, Jiaxing, China
3. Department of Immunization Program, Tongxiang Centre for Disease Control and Prevention, Tongxiang, China
4. Department of Immunization Program, Haining Centre for Disease Control and Prevention, Haining, China
5. Health Center of Huangwan Town, Haining, China