Impact of public health interventions to control an outbreak of pertussis in an elementary school — Pennsylvania, 2008

Background: Pertussis outbreaks occur even among highly vaccinated populations. On 9/15/2008, the Pennsylvania Department of Health (PADOH) was notified of a pertussis case in a 601-student elementary school with a highly vaccinated student population. We assessed the impact of evolving PADOH-recommended control measures. Methods: Cases were reported to PADOH by laboratorians and physicians, and later by parental interview of coughing students sent home by the school nurse. Pertussis was confirmed by 2 weeks of cough with paroxysms, whoop, or posttussive vomiting plus positive polymerase chain reaction (PCR) or epidemiologic link. Results: Of 53 confirmed cases, 26 were PCR-confirmed; attack rate was higher among upper grades (third–sixth, 11.0%) than lower grades (kindergarten–second, 5.3%) (P=0.007). On 9/15/2008, PADOH recommended excluding from school students with suspected pertussis, but the outbreak expanded rapidly. On 11/3/2008, the peak week of the outbreak, teachers were instructed to refer coughing students to the school nurse to be sent home, resulting in a 10% absentee rate. The next week, referral of coughers accelerated, and students were required to receive 5 days of antibiotic therapy before returning to school, increasing the absentee rate to 30%. The following week, no cases occurred. The only additional case had onset date of 12/3/2008. Conclusion: Active surveillance for cough illness and strict enforcement of exclusion and treatment might have contributed to the rapid decline in new cases. Although such policies might prove challenging for families and school officials, this outbreak demonstrated that the initial recommendations were insufficient to halt the outbreak.