Epidemiological characteristics of varicella after class C management and vaccination strategy in Nanjing,China
Objective To understand the epidemiological characteristics of varicella in Nanjing after Class C management and vaccination strategy,analyzing the effect of prevention and control measures,providing scientific basis for improving the prevention and control strategy.Methods We collected reported varicella cases data from 2013 to 2022 in Nanjing and utilizied the Joinpoint regression model to calculate the annual percent change(APC)and the average annual percent change(AAPC)in incidence rates.We described the characteristics of temporal distribution,population distribution,spatial distribution and spatial clustering of varicella in Nanjing from 2013 to 2022 by R program,and compared the changes of epidemiological characteristics between the Class C management(2017-2018)and the vaccination strategy(2019-2022).Results A total of 87 538 varicella cases were reported.The average annual reported incidence was 102.20/100 000,with the peak of 228.64/100 000(19 057 cases)in 2018,and declined to 98.32/100 000(9 262 cases)in 2022,with a decrease of 57.00％.The APC from 2013 to 2018 and from 2018 to 2022 were 71.47％(95％CI:41.96％-107.10％)、-15.36％(95％CI:-35.20％-10.54％),respectively,and the AAPC was 25.29％(95％CI:11.03％-41.37％).The median age of cases in 2019-2022[10(5,19)]was higher than that in 2017-2018[7(5,15)](P＜0.001),and the proportions of reported incidence reduction in each age groupunder 15 years old were between 57.46％and 90.46％,and the peak of incidence in the age group was reduced.The proportion of students,kindergarten children and scattered children decreased from 84.53％to 75.26％,among which the kindergarten children decreased from 32.51％to 28.85％,and the scattered children decreased from 11.13％to 5.55％.The incidence rate in the main urban areas were lower than that in the surrounding areas.After vaccination strategy,the most likely clusters changed from Jianye District,Jiangbei District,Yuhuatai District and Jiangning District to Gaochun District(P＜0.001).Conclusions The quality of varicella surveillance in Nanjing has been improved after class C management.After vaccination strategy,the reported incidence decreased significantly,and the population and spatial distribution characteristics changed.
VaricellaIncidence trendEpidemiologic characteristicsSpatial clusteringPrevention and control strategy
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