水痘免费接种策略对南京市水痘流行病学特征的影响分析

Analysis on influence of free vaccination strategy of varicella on epidemiological characteristics of varicella in Nanjing City

目的 了解2014-2021年南京市水痘流行病学特征及2018年11月水痘疫苗纳入南京市免疫规划后对流行特征可能的影响。方法 使用描述流行病学方法,对2014-2021年南京市水痘发病情况进行分析,通过χ2检验分析发病率变化。应用ArcGIS计算莫兰指数方法对南京市各地区发病率进行空间自相关分析。结果 2014-2021年南京市共报告水痘病例76 707例,水痘暴发疫情83起。水痘疫苗纳入免疫规划前后平均发病率分别为172.021/10万和154.972/10万,差异有统计学意义(χ2=205.157,P<0.05)。水痘暴发起数和病例数自2019年开始出现下降趋势,由2019年的29起681例下降至2021年5起160例,水痘公卫突发事件在全市公共卫生突发事件中的比例也由2018年的48.98%下降至2021年的35.71%。每年发病高峰为5-6月和11-12月,2021年冬季峰值为2017年以来的最低值,仅与当年5-6月高峰持平,发病人群主要为0~<11岁的幼托儿童和学生,但0~<5岁、5~<10岁儿童2021年发病率较2018年分别下降了72.64%和64.97%,全市仅2020年和2021年出现空间聚集性,莫兰指数分别为0.291及0.258。结论 水痘疫苗纳入免疫规划后水痘发病显著下降,应加大水痘疫苗免疫程序宣传力度,提高水痘疫苗的接种率。

Objective To analyze the epidemiological characteristics of varicella in Nanjing City from 2014 to 2021 and possible influence of varicella vaccine included in the Nanjing immunization plan in November 2018.Methods The descriptive epidemiological methods was used to analyze the incidence of varicella in Nanjing City from 2014 to 2021,andχ2 test was used to analyze the changes in incidence rate.The spatial autocorrelation analysis of incidence rate in different regions of Nanjing City was carried out by using ArcGIS to calculate Moran's I.Results From 2014 to 2021,totally 76707 varicella cases and 83 varicella outbreaks were reported in Nanjing City.The average incidence rate before and after the varicella vaccine included in the immunization plan was 172.021/100000 and 154.972/100000 respectively,and the difference was statistically significant(χ2=205.157,P<0.05).The number of outbreaks and related cases has declined since 2019,from 29 outbreaks and 681 cases in 2019 to 5 outbreaks and 160 cases in 2021.The proportion of public health emergencies caused by varicella to total public health emergencies has also decreased from 48.98%in 2018 to 35.71%in 2021.The peaks of incidence occurred from May to June and from November to December.The winter peak in 2021 was the lowest since 2017,which was only the same as the peak from May to June of that year.The cases mainly occurred in preschool children and students aged 0-<11 years old.However,the incidence rate of children aged 0-<5 and 6-<10 years old decreased by 72.64%and 64.97%respectively as compared with 2018.The spatial aggregation was only observed in 2020 and 2021,and the Moran's I was 0.291 and 0.258 respectively.Conclusion The incidence rate of varicella significantly reduced after varicella vaccine included in the immunization plan,and it is necessary to increase the publicity efforts for the vaccination program of varicella vaccine and increase the coverage rate of varicella vaccine.