Association Between Varicella Vaccination Status and Self-Reported Contact History Among Confirmed Varicella Cases in...

Objectives: To investigate associations between varicella vaccination and self-reported contact history with varicella or herpes zoster among clinically diagnosed varicella cases in Chaoyang District, Beijing, China. Methods: A retrospective observational study was conducted among 4441 clinically diagnosed varicella cases reported from 2017 to 2025. Multivariable logistic regression examined associations between vaccination status, number of doses, time since vaccination, and reported contact history with varicella and/or herpes zoster, adjusting for age, sex, and year of diagnosis. Results: Vaccinated cases had significantly higher odds of reporting contact with varicella or zoster compared with unvaccinated cases (OR = 1.34, 95% CI: 1.14-1.58). Both 1-dose and 2-dose recipients showed similar associations. A gradient of increasing odds was observed with longer time since vaccination, reaching OR = 3.17 (95% CI: 1.39-7.22) for 10 or more years since last dose. Associations were primarily driven by reported varicella contact rather than herpes zoster contact. Sensitivity analysis confirmed robustness of findings. Conclusions: Varicella vaccination was positively associated with reporting an identifiable exposure source. Vaccination status may influence completeness of exposure ascertainment in varicella surveillance and should be considered when interpreting contact tracing data.