1. EPI Department, Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
2. EPI Department, Shapingba District Center for Disease Control and Prevention, Chongqing, China
3. EPI Department, Yuzhong District Center for Disease Control and Prevention, Chongqing, China
4. EPI Department, Changshou District Center for Disease Control and Prevention, Chongqing, China
5. EPI Department, Jiulongpo District Center for Disease Control and Prevention, Chongqing, China
6. EPI Department, Yubei District Center for Disease Control and Prevention, Chongqing, China