Five-year immunity persistence following immunization with inactivated enterovirus 71 vaccine (Vero cell)#br#
Lu Weiwei, Meng Fanyue, Guo Huijie, Hao Chunsheng, Mao qunying, Gao Fan, Bian Lianlian, Duan Kai, Chen Xiaoqi, Li Xinguo, Chen Wei, Tao Hong, Chen Jinhua, Li Xiuling#br#
National Vaccine & Serum Institute, Beijing 100111, China; Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China; National Institute for Food and Drug Control, Beijing 102629, China; Wuhan Institute of Biological Products Co., Ltd., Wuhan 430070, China; Shanghai Institute of Biological Products Co., Ltd., Shanghai 200051, China
Abstract： Objective To investigate the immunity persistence five-year following two-dose vaccination of inactivated enterovirus 71 (EV71) vaccine. Methods For EV71 neutralizing antibody (NAb) testing, blood samples were collected from a subset of participants whose serum NAb assay was negative on day 0 in the immunogenicity cohort fulfilled the two doses vaccination protocol. The full series of sampling points included day 0, day 56, month 8, month 14, month 26, and month 64. Results 614 subjects completed blood sample collection and obtained NAb results. Combined with the previous observation, 490 subjects had the full series of sampling points including day 0, day 56, month 8, month 14, and month 64; with 235 vaccine subjects and 255 placebo subjects. 5 years after vaccination, the positive rates and the geometric mean titers (GMTs) of anti-EV71 NAb in vaccine group (100.00% and 369.57) were higher than those in placebo group (69.02% and 55.58). By the cutoff NAb titer values of 8, 16, 32, 5 years post the 1st vaccination, the seropositive rates in vaccine group (100.00%, 99.57%, 97.87%) were higher than those in placebo group (69.02%, 61.96%, 59.61%). In both 6-11 and 12-35 month subgroups, in vaccine group, 5 years post the 1st vaccination, the NAb seropositive (titer≥8) rates (both 100.00%) and GMTs (367.14, 370.64) were higher than those in placebo group (66.67%, 71.27%, and 63.66, 53.43). At all observed time points, the seropositive rates and GMTs in vaccine group were higher than that of placebo group. Conclusion The EV71 vaccine induces a sustained high level of NAb GMTs and seropositive rates against EV71 for at least 5 years in healthy Chinese children.
2020, Vol. 43 
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