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.

The original study included cases recorded from 01 January 2011 through 31 December 2014, based on retrospective case-control methodology.

Inclusion Criteria:

Cases were included if they met the following inclusion criteria:

• Reported pertussis disease in the referenced EIP surveillance database
• Age greater than 2 days and younger than two months of age
• Resided in the catchment area on date of onset of their cough
• Born in a hospital in their state of residence
• ≥ 37 weeks of gestation at birth
• Not adopted, in foster care or living in a residential care facility
• Completed maternal interview
• Completed infant and maternal information

Controls were included if they met the following inclusion criteria:

• Age greater than 2 days and younger than 2 months of age on date of cough onset for the corresponding case infant
• Resided in the catchment area on date of cough onset for the corresponding case infant
• Born in a hospital in their state of residence
• ≥ 37 weeks of gestation at birth
• Not adopted, in foster care or living in a residential care facility
• Maternal interview completed
• Infant and maternal information complete

Exclusion Criteria:

Cases were excluded if they met any of the following exclusion criteria:

• Vaccination status of the mother unknown
• Infants whose mothers were vaccinated with Boostrix or an unknown vaccine brand

Controls were excluded if they met any of the following exclusion criteria:

• Vaccination status of the mother unknown
• A pertussis diagnosis prior to the cough onset date of the corresponding case infant
• Controls that were matched to Boostrix or an unknown brand cases

Infants between 2 days to < 2 months of age for whom a case of pertussis was reported to one of 6 Emerging Infection Program (EIP) network sites included in the original Skoff et al. study (in 2017) and their respective control infants, for the study period.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org