Safety of Pertussis Vaccination in Pregnant Women in UK: Observational Study

This is an observational cohort study that measured the rates of adverse events in pregnant women and their fetuses/children after pertussis vaccination was given during the third trimester of pregnancy. After a peak in pediatric deaths secondary to pertussis in 2011 and 2012, the United Kingdom Joint Commission of Vaccination and Immunization instituted a vaccination program that targeted pregnant women between 28 and 38 weeks gestation. The safety of the vaccination was not originally evaluated in pregnant patients and this study was conducted to fill the gap in saftey data in that segment of the population. Data for the study were taken from the Clinical Practice Research Datalink (CPRD), which compiles data from > 650 primary care centers, serving > 12.5 million patients in the United Kingdom. The majority of pregnant women in the UK received vaccinations from physicians who report to the CPRD. Mother and child data are linked in the CPRD, which allowed for tracking outcomes in the child postpartum. A total of 20,074 pregnant women were given the pertussis vaccination in the first 6 months of the vaccination campaign; 17,560 of the women had data that was substantial enough for further evaluation and 13,371 had an estimated fetal age that was sufficient for data extraction. The median fetal age during vaccination was 31 weeks. All subjects were matched with up to three unvaccinated controls. There was no evidence of an increase in the risk of threatened labor, stillbirth, pre-eclampsia, or eclampsia either pre or post delivery in the vaccinated cohort. There were no changes in the time to delivery or the median birth rate in the vaccination group. There were no episodes of maternal death, uterine rupture, antepartum hemorrhage, vasa previa, placental abruption, fetal distress, or child renal failure in the vaccinated mother/children.