July 14, 2006 -- Varicella Outbreak Raises Questions about Vaccination, Surveillance

After a school nurse notified the Nebraska Health and Human Services System of an outbreak of chickenpox in an elementary school in 2004, the state initiated a retrospective study to determine the extent of the outbreak and the severity of the illness in both vaccinated and unvaccinated children. In a summary published in this week’s issue of the Morbidity and Mortality Weekly Report, the federal Centers for Disease Control and Prevention (CDC) notes that there has been a dramatic decline in cases of chickenpox since licensure of a vaccine in 1995 and implementation of a variety of school-entry varicella vaccination requirements in most states. To reduce additional virus transmission during an outbreak, the Advisory Council on Immunization Practices in 2005 recommended a second dose of varicella vaccine in outbreak settings for those who had previously received one dose of the vaccine. In addition, the Council of State and Territorial Epidemiologists recommended that by 2005, all states should have established case-based varicella reporting using either statewide surveillance or surveillance in sentinel sites. As demonstrated in the Nebraska outbreak, “schools are an ideal setting for varicella sentinel surveillance because of their readily available vaccination records and populations that can be surveyed easily,” the CDC said. The report, “Varicella Outbreak Among Vaccinated Children—Nebraska, 2004,” appears in the July 14, 2006, issue of Morbidity and Mortality Weekly Report at http://www.cdc.gov/mmwr.