Seroepidemiological survey of the population 10 years after the implementation of the varicella vaccine 2-dose immunization strategy.

Despite the implementation of a two-dose varicella vaccine (VarV) immunization strategy for over a decade in Quzhou, China, outbreaks of varicella continue to be reported in school settings with high vaccination coverage. This cross-sectional study surveyed healthy individuals aged 3 to 20 years across six districts and counties in Quzhou, China. Serum samples were collected to detect varicella-zoster virus (VZV) IgG antibodies and to evaluate the effectiveness of the two-dose VarV immunization strategy. Among the 1,020 participants, the overall seropositivity rate for VZV IgG was 57.16%, with a median concentration (MC) of 136.46 mIU/mL. Multivariable logistic regression analysis revealed that VZV IgG seropositivity was associated with residence, age group, and VarV immunization history. Single-dose recipients exhibited an antibody peak at 4.34 years, followed by decline to a nadir at 7.95 years and subsequent rebound. In two-dose recipients, antibody levels declined rapidly within the first 1.82 years post-vaccination, followed by a gradual downward trend; nevertheless, levels consistently remained above the protective threshold of 100 mIU/mL. The necessity of booster immunization warrants further investigation.