Vaccination coverage estimates and utilization patterns of inactivated enterovirus 71 vaccine post vaccine introduction in Ningbo, China

Background

In China, enterovirus 71 (EV71) is the major etiological agents of hand foot mouth disease that poses severe risks to children’s health. Since 2015, three inactivated EV71 vaccines have been approved for use. Previous studies indicated the high willingness of EV71 vaccination in eastern China. However, few studies have assessed coverage and utilization patterns of EV71 vaccine in China.

Methods

Children born during 2012–2018 were sampled and their records were abstracted from Ningbo childhood immunization information management system. Descriptive statistics characterized the study population and assessed coverage and timeliness for EV71 vaccination. Simultaneous administration patterns as well as type of EV71 vaccine used were also evaluated. Bivariate and multivariable analysis was used to examine the relationship of socio-demographic characteristics with vaccination coverage and timeliness.

Results

Of 716,178 children living in Ningbo. One hundred seventy-two thousand two hundred thirty-six received EV71 vaccine with a coverage rate of 24.05% and only 8.61% received vaccination timely. 21.97% of children received the complete two dose EV71 series but only 6.49% completed timely. Vaccination coverage and timeliness increased significantly from 2012 birth cohort to 2018 birth cohort. Relatively higher coverage and timeliness were observed in resident children, Inner districts, high socioeconomic areas and large-scaled immunization clinics. Of 329,569 doses of EV71 vaccine, only 5853(1.78%) doses were administered at the same day as other vaccines.

Conclusions

There is a need for increasing EV71 vaccination coverage and timeliness as well as eliminating disparities among different populations. Our study highlights the importance of simultaneous administration to increasing coverage and timeliness of EV71 vaccination.

[Post-marketing multi-center safety surveillance of inactivated enterovirus A71 vaccine (Vero cell)]

Objective: To evaluate the post-marketing safety profiles of the inactivated enterovirus type 71 (EV-A71) vaccine (Vero cell) after routine inoculation. Methods: Eleven cities of Zhejiang Province, Fengtai district of Beijing, Qinnan district, two counties as Pingle and Pingguo of Guangxi Zhuang Autonomous Region, and Dongtai city of Jiangsu Province were selected as the field sites. A total of 45 239 subjects were enrolled in this study from children who seeked the vaccination of EV-A71 vaccine during the period from July, 2016 to June, 2018. Different sampling method were adopted in different sites. All vaccinated children were invited to participate in the study in Fengtai and Dongtai, however, systematic sampling method were adopted in other sites. Active surveillance was conducted and information about adverse reactions (ARs) occurred in 30 min, 3 d and 30 d following each dose of EV-A71 immunization was collected by field observation, phone-call or face-to-face interview. The incidence of ARs in different types, symptoms and grades were described. Results: In total, there were 45 239 children who received 71 243 doses EV-A71 vaccine. The overall incidence of ARs was 1.079% (769 doses), with the highest incidence of 1.182% (177/14 973) in 5-11 month group and the lowest incidence of 0.849% (18/2 119) in ≥ 36 month group among different age groups. There was a higher incidence in solicited ARs, which was 1.047% (746 doses). The incidences of grade 1 and grade 2 ARs were also higher, which were 0.404% (288 doses) and 0.554% (395 doses), respectively. No grade 4 ARs occurred. The doses of the first and the second vaccination was 40 736 and 30 507, respectively, and the incidences of ARs were 1.281% (522 doses) and 0.810% (247 doses). Also, the incidences of ARs were 0.091% (37 doses) and 0.043% (13 doses) in local, and 1.168% (476 doses) and 0.760% (232 doses) in system. The symptoms of ARs after the two doses of vaccination were basically the same. Redness at the injection site was the most common local ARs after each dose vaccination, with doses of 24 and 11, while fever was the most common systemic ARs, with doses of 362 and 190. Moreover, ARs mainly occurred in 30 min to 3 d after each dose vaccination, with incidence of 1.016% (414 doses) and 0.698% (213 doses) in the first and second dose, respectively. Conclusion: The ARs had a low incidence after vaccination in children and most were mild or moderate. EV-A71 vaccine with good safety is suitable for inoculation in a large scale.