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The MMWR is embargoed until Thursday, 12 PM EST.
Varicella vaccine was 81 percent effective in preventing varicella during an elementary school outbreak with significantly milder disease among vaccinated students compared to unvaccinated students and warrants improving varicella vaccination coverage.
A varicella outbreak at an elementary school in Nebraska
in November 2004 raised concerns about vaccine failure among vaccinated
students. The public health investigation demonstrated that vaccine effectiveness
was within the expected range (80-85 perdent); and vaccinated cases had
significantly milder disease. Since the licensure of varicella vaccine
in the United States in 1995 and the subsequent nationwide implementation
of a varicella vaccination program there has been a dramatic decline in
cases, hospitalizations, and deaths related to varicella. However, varicella
outbreaks continue to occur, involving both unvaccinated and vaccinated
cases as was the case in this outbreak too. Implementation of broader school
entry requirements (to include students from kindergarten to college) can
increase vaccination coverage and reduce varicella morbidity. The Advisory
Committee on Immunization Practices (ACIP) recently recommended a second
dose of varicella vaccine for children 4-6 years old and a second dose
catch-up vaccination for children, adolescents and adults who previously
had received one dose. The second dose is expected to provide protection
to children (OR persons?) who do not adequately respond to the first dose
and have an impact on school outbreaks.
This page last reviewed November 9, 2006
Disease Control and Prevention