1.
Clin Infect Dis
; 35(1): 102-4, 2002 Jul 01.
Article
in English
| MEDLINE
| ID: mdl-12060885
ABSTRACT
In our investigation of a varicella outbreak among students in preschool, kindergarten, and grades 1-3 in Winnebago County, Illinois, we found an overall varicella vaccine efficacy of 88%, evidence that the circulating virus was a wild-type strain (as determined by polymerase chain reaction analysis), and evidence that vaccination of children =15 months of age was associated with an increased risk for breakthrough varicella (relative risk, 3.7; 95% confidence interval, 1.1-13.1; P=.04). The efficacy of varicella vaccine might be improved if administration of the initial vaccine dose is delayed until children are >/=15 months of age.