A Cross-Sectional Seroepidemiological Study on Varicella Zoster Virus in Zhejiang, China.

Objectives: This study aimed to investigate the levels of varicella antibodies in Zhejiang, China, after a decade of implementing the two-dose varicella vaccine (VarV) strategy. Methods: Healthy participants aged 1 to 69 years from Zhejiang, China, were recruited from January to April 2024 using multistage stratified random sampling, and varicella zoster virus (VZV) IgG antibodies were detected by ELISA. We assessed the seroprevalence and geometric mean concentration (GMC) of VZV IgG and analyzed related factors using Logistic and linear regression models. Results: A total of 807 participants were included in the study. The overall seropositivity rate for VZV IgG in the healthy population was 73.08% (95%CI: 69.87-76.11), with a corresponding GMC of 200.97 mIU/mL (95%CI: 182.75 mIU/mL-221.01 mIU/mL). Multivariate analysis identified age group, VarV immunization history, and history of varicella disease as factors significantly associated with both VZV IgG seropositivity and GMC levels (p < 0.05). The seropositivity rate for VZV IgG in children aged 1-14 years was 42.67% (95%CI: 36.22-49.31), with a corresponding GMC of 82.10 mIU/mL (95%CI: 69.14 mIU/mL-97.48 mIU/mL). Furthermore, a significant decline in both seropositivity and GMC was observed over time following vaccination among vaccinated children aged 1-14 years (p < 0.05). Conclusions: Two-dose VarV vaccination may be considered for inclusion in the national immunization program.