The original study included cases recorded from 01 January 2011 through 31 December 2014, based on retrospective case-control methodology.
The purpose of this study is to determine the effectiveness of Adacel against pertussis disease in infants < 2 months when administered during pregnancy following the current Advisory Committee on Immunization Practices (ACIP) recommendations, i.e., from 27 to 36 weeks of gestation, and 14 days or more before delivery.