Effect of influenza vaccination in a school with influenza A outbreak in Sichuan Province
Objective To investigate the protective effect of influenza vaccine in school influenza A outbreaks,and to provide evidence for the development of vaccination strategies.Methods All students from Shehong No.7 Primary School in Suining City,Sichuan Province,where the outbreak of influenza A occurred in February 2023,were selected.On March 9th～12th,2023,influenza incidence data were collected through on-site self-filling online questionnaires.Cases and controls were selected among students in classes with ≥3 incident cases to carry out a 1∶2 matching case-control study,and the Sichuan Immunization Planning Platform was queried to verify influenza vaccination information.The difference in vaccination rate between the two groups was compared by x2 tests,the OR value and vaccine effectiveness(VE)were calculated,and the dose-response relationship was analyzed by the M-H x2 test and Pearson correlation.The U-test was used to compare the median difference between the number of days of illness and the symptom score of the cases to analyze the effect of influenza vaccine on the severity of influenza cases(α=0.05).Results A total of 207 cases and 414 controls were included in the case-control study,and the VE of influenza vaccine of the current season and the past 3 years was 53.08％(95％CI:9.58％～75.65％)and 50.12％(95％CI:22.10％～68.06％),respectively.There was a dose-response relationship between influenza vaccination doses and morbidity in the past 3 years(x2=7.4,R=-0.11,P＜0.05).Compared with the unvaccinated group,the median course of disease in the current season vaccination group was shortened from 4 days to 3 days(Z=2.219,P=0.027),and the median symptom score decreased from 10 to 7 points(Z=3.123,P=0.002).Conclusions Influenza vaccination of both the season and the past 3 years has a moderate protective effect on preventing influenza,and the risk of influenza infection increases with the increase in the number of influenza vaccine doses in the past 3 years.Seasonal influenza vaccination can effectively shorten the course of disease and reduce clinical symptoms.
influenza Ainfluenza vaccineprotective effectSichuan Province
万方数据
维普
