This retrospective pregnancy case was reported in a literature article and described the occurrence of pertussis in a infant. The mother received dTpa vaccine. The infant was exposed to dTpa vaccine during the third trimester of pregnancy. The pregnancy resulted in a live neonate with no apparent congenital anomaly. The infant was diagnosed with pertussis. Serious criteria included GSK medically significant. Additional event(s) included maternal exposure during pregnancy, third trimester. The outcome of pertussis was recovered/resolved. The outcome(s) of the additional event(s) included maternal exposure during pregnancy, third trimester (unknown). The investigator considered that there was a reasonable possibility that the pertussis may have been caused by dTpa vaccine. Relevant Tests: Lab tests were performed on an unspecified date between, 2010 and 2015. Diagnostic results (unless otherwise stated, normal values were not provided): On an unknown date, Polymerase chain reaction result was positive for pertussis infection unknown. Additional information was provided. This retrospective pregnancy case was reported in a literature article and described the occurrence of pertussis infection in an infant aged less than 2 months of unspecified gender whose mother was vaccinated with unspecified Tdap (manufacturer unknown) during pregnancy. The patient and the mother were part of the retrospective cohort study of infants born from 2010 to 2015. The study estimated the effectiveness of maternal pertussis vaccination for protecting newborns against pertussis in the first 2 months of life and in the first year of life accounting for each infant DTaP dose. The patient was born between 2010 and 2015. The patient was born full term (more than or equal to 37 weeks gestation). The patient's mother was continuously enrolled in the study during pregnancy to ensure correct classification of Tdap status. The patient's mother was born before 1996 and had received whole cell rather than acellular pertussis vaccines for her primary series i.e in infancy. No information on patient's medical history or concurrent condition or concomitant medication was provided. On an unspecified date, at least 8 days (more than 7 days) before delivery, the patient's mother had received unspecified Tdap vaccine (administration site and route; dosages unknown; batch number not provided). Subsequently, the patient was exposed to the vaccine in utero. (In this study, maternal vaccines were counted beginning 8 days after receipt to allow time for the immune response). On an unspecified date after birth, an unknown period after maternal vaccine exposure, the patient was tested polymerase chain reaction (PCR) positive for pertussis infection. [Within 5 days before or after the PCR test, the patient received a diagnosis of cough or pertussis and/or had pertussis symptoms (eg, cough, apnea)]. The patient received a prescription for Azithromycin or Erythromycin. The patient was a breakthrough case in the study. (It is reported that since 2006, all pertussis testing has been conducted in a centralized laboratory using real-time polymerase chain reaction (PCR) on nasopharyngeal swabs). (In this study, within 30 days before or after the PCR test, out of 17 infants with pertussis in the first 2 months of life, 10 were hospitalized for pertussis, and an additional 3 had emergency department visits related or possibly related to pertussis. Out of 2 patients with Tdap exposure in utero, 1 case born to mother vaccinated during pregnancy had a mild illness and was treated as an outpatient). The patient recovered without sequelae. No death occurred in the study. The authors did not comment on the relationship between the event of pertussis infection and unspecified Tdap vaccination. The authors concluded that "Maternal Tdap vaccination during pregnancy was highly effective at protecting infants against pertussis before their first dose of DTaP vaccine, and protection continued after the first DTaP dose through the first year of life. We did not find evidence supporting the effectiveness of maternal postpartum cocooning with Tdap vaccine. Our study validates the current recommendation to vaccinate with Tdap during pregnancy, and suggests that widespread use of Tdap vaccination in pregnancy can result in significant decreases in pertussis, particularly in young infants before their first DTaP vaccine dose or who are protected by only 1 dose of DTaP". This is 1 of the 2 valid cases from the same literature article.