Peer-reviewed article
Effectiveness of One- and Two-Dose Varicella Vaccination Among Children and Adolescents Aged 0-18 Years - Chaoyang District, Beijing, China, 2007-2025.
Jianliang Zhao, Ziwei Zhao, Chaofan Wang, Yang Cao, Yeran Jiaerken et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study evaluated how well varicella (chickenpox) vaccines protect children and teenagers in Beijing, China between 2007 and 2025. Researchers tracked over 550,000 children and found that one dose of the vaccine prevented about 97% of varicella cases, while two doses prevented about 98%. Children who received two doses had much lower infection rates than those who received one dose or no vaccine at all.
Key points
- Incidence rate was 20.79 per 1,000 person-years in unvaccinated children, compared to 2.28 in one-dose and 0.34 in two-dose recipients
- Vaccine effectiveness was 96.8% for one dose and 98.2% for two doses
- Two-dose vaccination provided the most stable and lowest cumulative incidence during follow-up
- Males accounted for 56.2% of cases and had slightly higher infection risk than females
- Increasing vaccine dose number was significantly associated with lower infection risk
Limitations
This is a retrospective observational study using surveillance data, so it cannot establish causation as rigorously as a randomised trial. The study does not provide information about adverse effects of vaccination or cost-effectiveness of different vaccination schedules.
Abstract
INTRODUCTION: Varicella is a highly contagious respiratory disease caused by the varicella-zoster virus that predominantly affects children and is prone to outbreaks in congregate settings. This study evaluated the effectiveness of varicella vaccination among children and adolescents aged 0-18 years in Chaoyang District and examined factors associated with infection risk. METHODS: A retrospective cohort study was conducted among 551,980 children and adolescents born between 2007 and 2025 using varicella surveillance data from the Chaoyang District Center for Disease Control and Prevention. Incidence rates were calculated, and vaccine effectiveness was estimated using Cox proportional hazards models. RESULTS: Among the 551,980 participants, 9,170 varicella cases were identified. The incidence rate was 20.79 per 1,000 person-years (PY) in the unvaccinated group, 2.28 per 1,000 PY in the one-dose group, and 0.34 per 1,000 PY in the two-dose group. Increasing vaccine dose number was significantly associated with a lower risk of infection. The cumulative incidence of varicella was lowest and most stable in the two-dose group during follow-up. Vaccine effectiveness (VE) was 96.8% [95% confidence interval (CI): 95.7%, 97.6%] for one-dose vaccination and 98.2% (95% CI: 97.9%, 98.5%) for two-dose vaccination. Males accounted for 56.2% of cases and had a slightly higher infection risk than females. CONCLUSION: Two doses of varicella vaccine provided strong protection against varicella. These findings support efforts to increase two-dose vaccination coverage and optimize varicella immunization schedules.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- One-dose and two-dose varicella vaccination
- Population
- 551,980 children and adolescents born between 2007 and 2025 in Chaoyang District, Beijing, China
Key finding
One-dose vaccine effectiveness: 96.8% (95% CI: 95.7%, 97.6%)
Zhao et al. · PubMed (US National Library of Medicine) · 26 Jun 2026