Infant outcomes after exposure to Tdap vaccine in pregnancy: an observational study

Abstract

ObjectivePertussis vaccination during pregnancy has recently been recommended in both the USA and UK to prevent pertussis infection in infants. While there are no apparent safety concerns about the administration of Tdap vaccine during pregnancy, there is only limited safety data available. We aimed to closely monitor infants exposed to Tdap during pregnancy to look for any adverse outcomes that may be attributable to the vaccine.DesignThis was a prospective observational study, collecting information to evaluate the safety of Tdap vaccine for infants exposed during pregnancy. Infants were followed for between 6 and 12 months after birth, with 84% completing 12 months of follow-up. Information was obtained from objective sources including routine health visits and vaccination records wherever possible, as well as frequent parental reports.SettingThe Canterbury region of New Zealand.PatientsA cohort of 403 infants whose mothers had received Tdap vaccine.Main outcome measuresGestational age at birth, growth parameters, congenital anomalies, immunisation status and timeliness of immunisation, development of pertussis infection.ResultsThere were no significant differences in birth weight, gestational age at birth, congenital anomalies or infant growth as compared with baseline population data. Infants of mothers who had received the vaccine were more likely to receive their vaccinations on time during infancy. No cases of pertussis occurred in this cohort despite high rates of disease in the community. We have not found any adverse events attributable to vaccine exposure.ConclusionsThese data add to the growing pool of evidence that the administration of Tdap vaccine during pregnancy is an appropriate strategy for reducing the burden of pertussis in infants.Clinical trial registrationAustralia New Zealand Clinical Trials Registry ACTRN12613001045707.

Maternal vaccination against pertussis: a systematic review of the recent literature

“…Equally reassuring are the findings of other well-designed observational studies,50 51 64–66 including a US retrospective observational cohort study using data from two California Vaccine Safety datalinks,64 a more recent analysis from seven US Vaccine Safety Datalinks in the year following ACIP recommendations for antenatal Tdap vaccination,50 a retrospective review of medical records of 1759 women who delivered a singleton infant in Texas during 2012–201465 and a prospective follow-up study of 403 infants in New Zealand whose mothers had received Tdap antenatally following a pertussis epidemic in 2012 67…”

Safety of Maternal Immunization Against Pertussis: A Systematic Review

“…Outcomes assessed included preterm birth, stillbirth, development-related parameters such as low/very low birth weight or small size for gestational age, neonatal death, birth defects (including atrioventricular septal defect, spina bifida, cleft palate, cleft lip and diaphragmatic hernia), major malformations, congenital anomalies, neonatal complications, respiratory disorders, APGAR score, and cord blood pH values (Table 1). No significant increase in any of these outcomes were identified among infants of Tdap-vaccinated compared to non-vaccinated pregnant women, or from expected norms, regardless of design (database analysis vs. clinical trial), population, or setting [13,41,43,50,[52][53][54][55][56]58]. In addition, no differences in the rates of serious adverse outcomes were observed in infants of Tdap-and Td-vaccinated pregnant women, and none of the serious adverse outcomes reported were considered related to vaccination [35].…”

“…Other pregnancy outcomes, including preeclampsia/eclampsia, intrauterine growth retardation, premature labor/contraction, postpartum hemorrhage, placenta previa, elective and spontaneous abortions, oligohydramnios, proteinuria, venous thromboembolism, cardiac events, and gestational hypertensive disorder have also been evaluated. These adverse events were not significantly increased among Tdapvaccinated vs. non-vaccinated pregnant women across multiple database analyses [42,43,47,48,50,[53][54][55][56] and clinical studies [13,41,58], even when consecutive doses of Tdap vaccine were repeated at intervals of \ 5 years [55]. Although Layton et al [43] found a small increase in postpartum hemorrhage in Tdap vaccinated compared with unvaccinated pregnant women (RR = 1.23; 95% CI 1.18-1.28) [43], the database analyses of Donegan et al [53] and Griffin et al [48] found no such increase with vaccination.…”

Fundamentals of Clinical Pharmacology With Application for Pregnant Women

“…Killed pertussis is one of the components of the Tdap vaccine. Infants are at the greatest risk for significant morbidity and mortality, with newborns having the highest rates of hospitalizations and deaths of any age group . Infants cannot be vaccinated until 2 months of age, and immunity does not appear until 6 months, leaving them vulnerable to whooping cough until that time.…”

“…Infants cannot be vaccinated until 2 months of age, and immunity does not appear until 6 months, leaving them vulnerable to whooping cough until that time. Recent research shows that Tdap vaccination during pregnancy may be 91% effective in preventing pertussis in infants, with antibodies remaining in the infant up to 6 weeks after birth . While more studies are needed to solidify the evidence that the Tdap vaccine during pregnancy does prevent infant pertussis, current evidence strongly supports the potential for decreased hospitalizations and deaths.…”