Single-dose varicella vaccine effectiveness in school settings in China

Vaccine
Volume 31, Issue 37, Pages 3763-4054 (20 August 2013)
http://www.sciencedirect.com/science/journal/0264410X/31/37

Single-dose varicella vaccine effectiveness in school settings in China
Original Research Article
Pages 3834-3838
Zhe Wang, Huili Yang, Keli Li, Aihua Zhang, Zijian Feng, Jane F. Seward, Stephanie R. Bialek, Chengbin Wang

Abstract
Background
Varicella vaccine has been available in the private sector in China for a decade as a single-dose regimen, but varicella vaccine effectiveness (VE) has not been fully examined in school settings yet.

Methods
A matched case–control study was carried out in elementary schools and daycares in Tai’an prefecture, Shandong province, China. Clinical diagnosis of varicella and breakthrough disease was used for this study. Four controls were randomly selected from classmates; two from classmates of the case and two from another class of the same grade without cases. Vaccination status, date of vaccination, and vaccine product received if vaccinated were collected from home and clinic immunization records. Vaccination status of all students in schools/daycares with varicella cases from home immunization records or parental recall was used to calculate vaccination coverage.

Results
The overall varicella VE was 83.4% (95% confidence interval 71.4–90.3%). Receipt of varicella vaccine five years or more years before the outbreak was significantly associated with breakthrough varicella (odds ratio = 4.7, P < 0.001), while age at vaccination (<15 vs. ≥15 months) was not (odds ratio = 1.5, P = 0.62). Varicella vaccination coverage was 41% with substantial variation across schools (range of 0–93.8%).