Safety Study And Related Case Surveillance Of EV71 Inactivated Vaccine In Chaoyang District, Beijing

Objective:1.To analyze the safety of EV71 inactivated vaccine in Beijing chaoyang district.Furthermore,the occurrence of rare and extremely rare adverse events after EV71 inactivated vaccine inoculation in an expanded population was further monitored.2.To compare the incidence of hand-foot-and-mouth disease(HFMD)caused by EV71 vaccine between the population receiving EV71 vaccine and the unvaccinated population,and explore the protective effect of the vaccine.Methods:1.The healthy infants aged 6?71 months,eligible for vaccination on voluntary and self-supporting principle and vaccinated from Aug.2016 to Dec.2017,were chosen for survey and the total sample size of subjects was not less than 20,000.In the study on safety according to the clinical phase ? trial,all subjects were administrated with two doses of the vaccine(day 0,30)without control group and blindness,observed post vaccination within 30 min and followed up on day 1,3,7 and 30 for advert events recorded on the AEFI Active Monitoring Survey Form.2.The cases of hand-foot-and-mouth disease(HFMD)were monitored in time with the Digital Epidemiological Survey System,collecting the samples of nasopharyngeal swabs and stools,confirming the cases with laboratory assay,evaluating and comparing the incidence of EV71 vaccinated subjects with that of EV71 unvaccinated ones,calculating the protective efficacy of the vaccine,inputting the data with ORACLE software and treating them with SQL software.Results:Among the total 25,995 qualified survey forms,23,478 subjects were accepted two doses of vaccines,3.59%of which had advert events observed(3.48%solicited)and 1092 cases of adverse events of which occurred post the first vaccination.Most of adverse events were mild and majority of serious adverse events were grade ? febrile and recovered subsequently.The results of the study showed the difference of the incidence of systematical adverse events of subjects between within 30 minutes,from 30 minutes to 3 days and from 4 days to 28 days post vaccination had statistical significance.No statistical difference of those was observed between sexes or ages and significant difference of those done between post the first dose of vaccination and the second as well as that had statistical significance.Except that the incidences of systematical adverse events of subjects aged 36?71 months had difference of statistical significance,those of subjects of other ages including local adverse events had no statistically significant difference,possibly relevant to tolerance of the children of the age group.The incidences of local swollen and induration of subjects between post the first dose of vaccination and the second had statistically significant difference while those of local rash of them had no statistically significant difference,the incidence of those post the second dose of vaccination being lower,suggesting some generation of toleration.The incidences between various adverse events with various redness,swollen and pain with various grades had statistically significant differences,respectively,the first grade of those being majority,suggesting good safety of the vaccine.The protective efficacy of the vaccine was 97.74%,being accordance with the results of the clinical trial phase ? with the vaccine.No matter what sex subjects' group(male or female)was,the incidence of the HFMD cases between vaccinated and unvaccinated groups had statistically significant differences.The 7 mild HFMD cases in vaccinated group occurred and 308 mild in unvaccinated group did,being statistically significant difference and evidence of protective efficacy of the vaccine from HFMD caused by EV71.The incidence of the HFMD cases in urban was lower than those in suburban or countryside,suggesting HFMD relevant to the life styles of ones.Conclusion:The evidences show the vaccine has good safety and protective efficacy for prophylactic vaccination post marketing and majority of adverse events are mild and good for extensive use further.It is necessary to observe the rare adverse event with vaccine use extensively for no observation of rare and extremely rare adverse event observed on this study.The vaccine has good protective efficacy from HFMD caused by EV71.