Epidemiological characteristics of varicella in Karamay City of Xinjiang from 2015 to 2022

ObjectiveTo analyze the epidemiological characteristics of varicella in Karamay City, to inform the prevention and control of the local varicella epidemic, and to guide adjustments to the varicella vaccine immunization strategy.MethodsThe data on varicella cases from 2015 to 2022 in Karamay were collected and the epidemiological characteristics were analyzed.ResultsA total of 3 380 varicella cases were reported in Karamay from 2015 to 2022, with an average annual incidence rate of 94.91/105. The incidence of varicella showed a year-on-year downward trend from 2015 to 2022 (AAPC=-16.29%, P<0.05). Varicella cases demonstrated a seasonal variation, with peak incidence occurring from October to January of the following year and a slight increase from April to June. There were regional differences in the distribution of incidence rate, with 109.68/105 in Karamay District, followed by 89.06/105 in Baijiantan District, and 53.80/105 in Dushanzi District, respectively. The incidence rates in the 10‒14 and 5‒9 years age groups were higher than that in other age groups, with an incidence rate of 447.01/105 and 422.33/105 in each group, respectively. Most of the cases were students, accounting for 59.17% of the total cases, followed by preschool children (17.40%). There were 645 breakthrough cases of varicella, accounting for 19.08% of the total cases. The average interval between the onset of breakthrough cases and the most recent vaccination was (5.77±3.43) years.ConclusionVaricella cases mainly occurred in schools and childcare institutions in Karamay City, highlighting the need for enhanced prevention and control efforts in these settings. A second dose of varicella vaccine is recommended for children before primary school enrollment.