Use of mass Tdap vaccination to control an outbreak of pertussis in a high school--Cook County, Illinois, September 2006-January 2007

On September 6, 2006, the Cook County Department of Public Health (CCDPH) was notified that a local high school student aged 17 years had pertussis. During September 2006-January 2007, 36 pertussis cases directly linked to the high school were identified. Because Bordetella pertussis immunity from childhood vaccinations wanes over time, outbreaks of pertussis can periodically occur among students and staff at middle and high schools. School settings facilitate transmission of pertussis, disrupting school and community activities and putting vulnerable populations, such as unvaccinated infants, at risk. A pertussis booster vaccine suitable for adolescents and adults became available in the United States in 2005, when two new tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines were licensed for persons aged 10-18 years and 11-64 years, respectively. In 2006, the Advisory Committee on Immunization Practices (ACIP) recommended that all adolescents and adults receive a one-time Tdap booster vaccination. This report summarizes strategies used to control the pertussis outbreak in Cook County, Illinois, including efforts to increase Tdap vaccination coverage. Despite multiple communications recommending Tdap vaccination and implementation of a cough exclusion policy during the pertussis outbreak, student vaccination rates did not increase substantially until a school-based Tdap vaccination clinic was implemented. Because persons at risk for pertussis might not seek vaccination from their usual health-care provider, even during an outbreak, local health departments might consider early implementation of a cough exclusion policy and on-site Tdap vaccination clinic as control measures.