In late June 2006, clusters of pertussis cases occurred in schools in two municipalities in the Vaucluse department. Because the school holidays were approaching, cases were identified very quickly so that control and prevention measures could be implemented. Serological results were initially collected through self-reporting and subsequently verified using documentation. In the first municipality, 13 cases occurred in June across four different schools. However, after verifying the serology results, none of the cases met the case definition criteria. In the other municipality, a single school was affected, with 14 cases. Of the 7 serology results reported as positive, 3 were verified, and one was positive. The vaccine’s efficacy was deemed adequate. No link could be identified between the cases in the two municipalities. This investigation highlighted the need to identify cases as early as possible and in a prospective manner in order to stop the circulation of the pathogen. A case definition that is less specific than the one currently proposed by the French High Council for Public Health—and therefore more sensitive—could enable primary care physicians to make a diagnosis quickly. The new recommendations in the 2008 vaccination schedule will help address the lack of availability of monovalent vaccine in France, which made it difficult to implement management measures, particularly adhering to the intervals between injections of combined vaccine preparations. Finally, it is imperative to remind healthcare professionals that the primary objective of managing pertussis cases is to protect vulnerable individuals. (R.A.)