基于screening method法6~72月龄儿童流感流行季流感疫苗效果评价

Effectiveness of influenza vaccine inoculation during 2016-2018 flu seasons among 6-72 months old children:a screening method analysis

目的基于screening method法评价6~72月龄儿童流感流行季流感疫苗效果(VE),为中国流感疫苗接种方案的制定和完善提供科学参考。方法收集中国流感监测信息系统中浙江省永康市和义乌市2016-2018年流感流行季(每年10月至次年4月)6~72月龄儿童流感确诊病例,通过国家免疫规划信息系统查询病例的流感疫苗接种记录,获得流感病例中流感疫苗接种比例(PCV)及参照人群(6~72月龄儿童)流感疫苗接种率(PPV),计算粗VEcrude值;应用广义线性模型(GLM)估算调整VEadjusted值及其95%CI。结果浙江省永康市和义乌市2016-2018年2个流感流行季共确诊6~72月龄儿童流感病例458例,剔除流感疫苗接种史不详者53例和流感发病与疫苗接种时间间隔<14 d者2例后,共403例纳入本研究。2016-2017年流行季流感病例为277例,PCV为6.1%,PPV为7.7%,VEcrude值为22.1%,VEadjusted值为30.6%(95%CI=-198.8%~83.9%);2017-2018年流行季流感病例为126例,PCV为4.0%,PPV为9.2%,VEcrude值为58.9%,VEadjusted值为55.1%(95%CI=-11.0%~81.8%)。按月龄分层分析结果显示,2016-2017年和2017-2018年流行季6~35月龄儿童流感病例分别为135和57例,PCV分别为3.0%和5.3%,PPV分别为3.4%和6.6%,VEcrude值分别为12.1%和20.8%,VEadjusted值分别为16.0%(95%CI=-129.0%~69.2%)和11.2%(95%CI=-190.4%~72.9%);2016-2017年和2017-2018年流行季36~72月龄儿童流感病例分别为142和69例,PCV分别为9.2%和2.9%,PPV分别为11.1%和11.3%,VEcrude值分别为18.9%和76.6%,VEadjusted值分别为32.2%(95%CI=-120.2%~79.1%)和74.4%(95%CI=-5.3%~93.8%)。结论浙江省永康市和义乌市2017-2018流行季VE值高于2016-2017流行季,2个流行季中36~72月龄儿童VE值均高于6~35月龄儿童。

Objective To estimate vaccine effectiveness(VE)of seasonal influenza vaccine inoculation during influenza seasons among children aged 6 to 72 months using screening method and to provide references for developing and improving the seasonal influenza vaccination in China.Methods We extracted the data on registered 6-72 months old influenza cases during flu seasons of 2016-2017 and 2017-2018(from October in a year to April of the next year)in Yongkang and Yiwu city of Zhejiang province from China Influenza Surveillance Network.The information on influenza vaccine inoculation of the flu cases and those of all the children aged 6-72 months were checked in National Immunization Planning Information Management System to calculate the proportion of cases vaccinated(PCV)and the proportion of population vaccinated(PPV).A crude vaccine effectiveness(VE)value was estimated by PCV and PPV using the formula based on screening method.Then,the adjusted VE and its 95% confidence interval(CI)were estimated using generalized linear models(GLM).Results Of the 458 influenza cases registered during the two flu seasons,403 were included in the analysis after excluding53 with unknown vaccination status and 2 with an interval less than 14 days between the vaccination and the flu incident.For the flu season of 2016-2017,totally 277 influenza cases were registered;the PCV and PPV were 6.1% and 7.7%;the crude VE was 22.1%;the adjusted VE(95%CI)was 30.6%(-198.8%-83.9%).For the flu season of 2017-2018,totally 126 influenza cases were registered;the PCV and PPV were 4.0%and 9.2%;the crude VE was 58.9%;the adjusted VE(95%CI)was 55.1%(-11.0%-81.8%).During the 2016-2017 and 2017-2018 flu season for the children aged 6-35 months,the number of registered influenza cases were 135 and 57;the PCV were 3.4% and 5.3%;the PPV were 3.4% and 6.6%;the crude VE were 12.1% and 20.8%;the adjusted VE were 16.0%(95%CI:-129.0%-69.2%)and 11.2%(95%CI:-190.4%-72.9%);while,for the children aged 36-72 months,the number of registered influenza cases were 142 and 69;the PCV were 9.2% and 2.9%;the PPV were 11.1% and 11.3%;the crude VE were 18.9% and 76.6%;and the adjusted VE was 32.2%(95%CI:-120.2%-79.1%)and 74.4%(95%CI:-5.3%-93.8%),respectively.Conclusion Among the 6-72 months old children in Yongkang and Yiwu city of Zhejiang province,the vaccine effectiveness of seasonal influenza vaccine during the 2017-2018 flu season is higher than that during 2016-2017 flu season and the vaccine effectiveness is higher among the children aged 36-72 months than that among those aged 6-35 months.