1. Department of Preventive Medicine, Guangdong Medical University, Dongguan, China
2. Maternal and Child Research Institute, Women and Children’s Hospital Affiliated to Guangdong Medical University (Shunde District Maternal and Child Health Hospital), Foshan, China
3. School Clinic, Guangdong Medical University, Dongguan, China
4. Department of Epidemiology and Biostatistics, Guangdong Medical University, Dongguan, China
5. Department of Immunization Program, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
6. Public Health Office, Dalang Town Community Health Service Center, Dongguan, China
7. Microbiology and Immunology, Guangdong Medical University, Dongguan, China
8. Neonatal Department, Shenzhen Maternal and Child Health Hospital Affiliated to Southern Medical University, Shenzhen, China