Assessing vaccine effectiveness for varicella in Wuxi, China: a time-series analysis

Abstract

Objective

The varicella vaccine is not included in the national childhood immunization schedules in China. Varicella epidemics and outbreaks are frequently reported, and the evidence for the effectiveness of the varicella vaccine remains unclear. The aim of this study was to investigate varicella vaccine effectiveness in Wuxi, China.

Methods

Varicella surveillance data were extracted from the China Information System for Disease Control and Prevention, and vaccination data were obtained from the Vaccination Integrated Service Management Information System of Jiangsu Province, China. Time-series analysis approaches were used to estimate varicella vaccine effectiveness.

Results

A total of 16,093 varicella cases among children aged 1–6 years between January 2016 and December 2020 were analysed. A total of 217,297 children completed a two-dose varicella vaccination series. Compared with districts with lower vaccination rates, districts in Wuxi with higher varicella vaccination rates had a lower proportion of cases (p < 0.001). In the time-series approach, 0.8% fewer varicella cases were associated with a 1% increase in the two-dose varicella vaccination rate (p < 0.001), and similar effects were found in both the male and female populations.

Conclusions

Two-dose varicella vaccination was recommended as an effective health intervention to prevent varicella in Wuxi, China. Varicella vaccination is urgently needed in routine childhood immunisation programs.

KEY MESSAGES

The introduction of two-dose varicella vaccination was an effective intervention to prevent varicella in Wuxi, China.

Varicella vaccination is urgently needed in routine childhood immunization programmes.

Keywords:

• Varicella
• vaccination
• vaccine effectiveness

Ethical approval

This investigation was conducted by public health agencies as part of their legally authorized mandate and was therefore considered minimal-risk research. No confidential information was involved and the study was exempted from ethical approval by the Institutional Review Board Wuxi Centre for Disease Control and Prevention.

Authors’ contributions

The authors’ responsibilities were as follows: XHZ designed the study, instructed the data analysis and critically reviewed the manuscript, and approved the final manuscript as submitted. LLW did the data cleaning and analysis, drafted and finished the manuscript. XY, XWW, and PS established the database, planned the data analysis and reviewed and revised the manuscript. All authors read and approved the final manuscript as submitted.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

No financial assistance was received in support of the study.