Epidemiological characteristics of varicella in Songjiang District， Shanghai from 2013 to 2021

Abstract

ObjectiveTo evaluate the effectiveness of the varicella vaccine immunization strategy in Shanghai， and to provide evidence for enhancing prevention and control measures by analyzing the incidence and trends of varicella in Songjiang District， Shanghai from 2013 to 2021.MethodsA descriptive analysis was conducted on 12 417 varicella cases reported in Songjiang District between 2013 and 2021. The epidemiological distribution of varicella cases was described， and the incidence rates were compared among different demographic variables， including registered residence， gender， age， and occupation.ResultsA total of 12 417 varicella cases were reported in Songjiang District from 2013 to 2021，with an average annual incidence of 77.03/105. The incidence of varicella showed an increasing trend from 2013 to 2017 （χ2trend=19.39， P<0.001）， followed by a subsequent decrease from 2017 to 2021（χ2trend=758.62， P<0.001）. Varicella cases demonstrated significant seasonal variation， with peak incidences occurring in April to May and November to January of the following year. The incidence rate among local residents was higher than that among non-local residents （χ2=2 935.58， P<0.001）. Most （38.59%） of the cases were students aged between 5 and 9 years old， accounting for 23.45% of the total cases. However， the age distribution of cases varied over the years （χ2=615.57， P<0.001）， and the incidence among children aged 5 to 9 years showed a declining trend since 2017.ConclusionThe overall incidence of varicella in Songjiang District exhibites a declining trend in recent years. Although varicella primarily affects children， there have notable changes in the age distribution. Adjustment of the immunization strategy for varicella vaccines in Shanghai effectively reduces the proportion of school-age subjects.

Keywords

• varicella
• epidemiology
• analysis