


,

* Epidemic Intelligence Service, Epidemiology Program Office
¶ Viral Vaccine-Preventable Diseases Branch, Epidemiology and Surveillance Division, National Immunization Program
** Division of Applied Public Health Training, Epidemiology Program Office

National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
Utah Department of Health, Salt Lake City, Utah
Salt Lake Valley Health Department, Salt Lake City, Utah
|| University of Utah School of Medicine and Primary Childrens Medical Center, Salt Lake City, Utah
Objectives. In the context of a chickenpox outbreak involving 2 Utah elementary schools, we conducted an investigation to assess vaccine effectiveness, describe illness severity, and examine risk factors for breakthrough varicella (ie, varicella in those who have been vaccinated).
Methods. All parents were asked to complete a questionnaire about their childs medical history. Parents of children with recent varicella were interviewed, and vaccination records were verified. Lesions were submitted for polymerase chain reaction testing.
Results. Questionnaires were returned for 558 (93%) of 597 students in school A and 924 (97%) of 952 students in school B. A total of 83 schoolchildren (57 unvaccinated and 26 vaccinated) had varicella during the October 2002 through February 2003 outbreak period. An additional 17 cases occurred among household contacts, including infants and adults. Polymerase chain reaction analysis recovered wild-type varicella. Vaccine effectiveness was 87%. With 1 notable exception, vaccinated children tended to have milder illness. Risk factors for breakthrough varicella included eczema, vaccination
5 years before the outbreak, and vaccination at
18 months of age. Restricting analysis to children vaccinated
5 years before the outbreak, those vaccinated at
18 months of age were more likely to develop breakthrough varicella (relative risk: 9.3; 95% confidence interval: 1.368.9).
Conclusions. The vaccine, administered by >100 health care providers to 571 children during a 7-year time period, was effective. Risk factors for breakthrough varicella suggest some degree of biological interaction between age at vaccination and time since vaccination.
Key Words: pediatrics school-age population vaccination varicella-zoster virus
Abbreviations: PCR, polymerase chain reaction ARU, attack rates among the unvaccinated ARV, attack rates among the vaccinated RR, relative risk CI, 95% confidence interval
This article has been cited by other articles:
![]() |
S. S. Chaves, P. Gargiullo, J. X. Zhang, R. Civen, D. Guris, L. Mascola, and J. F. Seward Loss of Vaccine-Induced Immunity to Varicella over Time N. Engl. J. Med., March 15, 2007; 356(11): 1121 - 1129. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. T. D'Angio, P. A. Boohene, A. Mowrer, S. Audet, M. A. Menegus, D. S. Schmid, and J. A. Beeler Measles-Mumps-Rubella and Varicella Vaccine Responses in Extremely Preterm Infants Pediatrics, March 1, 2007; 119(3): e574 - e579. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. M. Davis, M. Marin, A. E. Cowan, D. Guris, and S. J. Clark Physician Attitudes Regarding Breakthrough Varicella Disease and a Potential Second Dose of Varicella Vaccine Pediatrics, February 1, 2007; 119(2): 258 - 264. [Abstract] [Full Text] [PDF] |
||||