Introduction of inactivated poliovirus vaccine leading into the polio eradication endgame strategic plan; Hangzhou, China, 2010-2014.
China's Expanded Program on Immunization (EPI) has provided 4 doses of oral poliovirus vaccine (OPV) since the 1970s. Inactivated poliovirus vaccine (IPV) became available in 2010 in Hangzhou as a private-sector, parent-chosen alternative to OPV. In 2015, WHO recommended that countries with all-OPV vaccination schedules introduce at least one dose of IPV, to mitigate risk associated with the withdrawal of type 2 OPV. We analyzed polio vaccine coverage and utilization in Hangzhou to determine patterns of IPV use and the occurrence of vaccine-associated paralytic polio (VAPP) in the various patterns identified.



Children born between 2010 and 2014 and registered in Hangzhou's Immunization Information System (HZIIS) were included. VAPP cases were detected through the acute flaccid paralysis surveillance system. We used descriptive epidemiological methods to determine IPV and OPV usage patterns and VAPP occurrence.



HZIIS data from 566,894 children were analyzed. Coverage levels of polio vaccine were greater than 92% for each birth cohort. Percentages of children using OPV-only, IPV-only, and IPV/OPV sequential schedules were 70.57%, 27.01% and 2.41%, respectively. IPV-only schedule utilization increased by birth cohort regardless of geographical area or whether the child was locally-born. The highest use of an all-IPV schedule (79.85%) was among urban, locally-born children in the 2014 birth cohort. Five VAPP cases were identified during the study years; all cases occurred following the first polio vaccine dose, which was always OPV for the cases. Type 2 vaccine virus was isolated from 2 VAPP cases, and type 2 and type 3 vaccine virus was isolated from one VAPP case. The incidence of VAPP in the 2010-2014 birth cohorts was 3.76 per 1million doses of OPV.



Children in Hangzhou had high polio vaccination coverage. IPV-only schedule use increased by year, and was highest in urban areas among locally-born children. All cases of VAPP were associated with the first dose of OPV.
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: smileforever81@126.com.
Yan
Y
Liu
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: 33250411@qq.com.
Jun
J
Wang
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: 526037475@qq.com.
Shijun
S
Liu
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: 1330297614@qq.com.
Jian
J
Du
Department of Emergency Management, Chengdu Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China. Electronic address: 363686849@qq.com.
Liang
L
Wang
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: 83912246@qq.com.
Wenwen
W
Gu
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: 1085731779@qq.com.
Yuyang
Y
Xu
World Health Organization China Office, Beijing 100600, China. Electronic address: zuosh@who.int.
Shuyan
S
Zuo
Department of Immunization, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, Zhejiang, China. Electronic address: zjhzxuep@163.com.
Erping
E
Xu
Department of National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing 100050, China. Electronic address: anzj@chinacdc.cn.
Zhijie
Z
An
D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D060740:Disease Eradication; D005260:Female; D006291:Health Policy; D006801:Humans; D017589:Immunization Programs; D007115:Immunization Schedule; D008297:Male; D011051:Poliomyelitis / Q000453:epidemiology / Q000517:prevention & control*; D017955:Poliovirus / Q000302:isolation & purification; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage* / Q000009:adverse effects; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage / Q000009:adverse effects; D000073887:Vaccination Coverage
D011054:Poliovirus Vaccine, Inactivated; D011055:Poliovirus Vaccine, Oral
Poliovirus vaccine; VAPP; Vaccination