A Retrospective Cohort Study of Safety Outcomes in New Zealand Infants Exposed to Tdap Vaccine in Utero

Abstract

We aimed to evaluate the safety of maternal Tdap; thus, we assessed health events by examining the difference in birth and hospital-related outcomes of infants with and without fetal exposure to Tdap. This was a retrospective cohort study using linked administrative datasets. The study population were all live-born infants in New Zealand (NZ) weighing at least 400 g at delivery and born to women who were eligible for the government funded, national-level vaccination program in 2013. Infants were followed from birth up to one year of age. There were a total of 69,389 eligible infants in the cohort. Of these, 8299 infants were born to 8178 mothers exposed to Tdap (12%), primarily between 28 and 38 weeks gestation as per the national schedule. Among the outcomes, we found a reduced risk for moderate to late preterm birth, low birth weight, small for gestational age, large for gestational age, respiratory distress syndrome, transient tachypnea of newborn, tachycardia or bradycardia, haemolytic diseases, other neonatal jaundice, anaemia, syndrome of infant of mother with gestational diabetes, and hypoglycemia in infants born to vaccinated mothers. There was no association between maternal Tdap, infant Apgar score at 5 min after birth, asphyxia, sepsis or infection, or hypoxic ischemic encephalopathy. Infant exposure to Tdap during pregnancy was associated with a higher mean birthweight (not clinically significant) and higher odds for ankyloglossia and neonatal erythema toxicum diagnoses. There were insufficient observations to allow examination of the effect of Tdap on extreme preterm and very preterm birth, and stillbirth, infant death, or microcephaly. Overall, we found no outcomes of concern associated with the administration of Tdap during pregnancy. NZ Health and Disability Ethics Committee Approval #14/N.T.A/169/AM05.

Obstetric and perinatal health outcomes after pertussis vaccination during pregnancy in Ontario, Canada: a retrospective cohort study

“…Our results concur with evidence that Tdap vaccination during pregnancy is not associated with poor perinatal outcomes, such as preterm birth, 17,19,21,22,25,27,28,48,49 being small for gestational age 19,22,27,48 and stillbirth. 17,19,21,23,[31][32][33] Although the reduced risks of a neonatal intensive care unit stay exceeding 24 hours and neonatal morbidity may have been due to nonspecific beneficial effects of maternal Tdap vaccination (i.e., vaccine protection beyond the targeted disease 50 ), limited evidence supports this in the context of maternal vaccination.…”

“…19 A New Zealand study of about 70 000 infants showed a reduction in respiratory distress syndrome (adjusted odds ratio 0.65, 95% CI 0.52-0.81) among Tdap-vaccine-exposed infants compared to unexposed infants. 22 Evidence on Tdap vaccination during pregnancy and chorioamnionitis is inconsistent. Three studies showed a small increased risk of chorioamnionitis among Tdap-vaccinated women; none showed increased risks for adverse infant outcomes typically associated with chorioamnionitis, such as preterm birth.…”

Case-Control Study to Estimate the Association Between Tdap Vaccination During Pregnancy and Reduced Risk of Pertussis in Newborn Infants in Peru, 2019–2021

“…The Tdap VE was calculated as 1− OR × 100%. Sex and age of the infant and mother at delivery were included as a priori confounders [ 33 ]. The region variable was selected to adjust for temporal and spatial variations in vaccine coverage [ 32 ].…”

Increasing Uptake of Maternal Pertussis Vaccinations through Funded Administration in Community Pharmacies

“…Only including women who were 28-38 weeks' gestation entirely in the pre-intervention or post-intervention periods avoided overlap in the pertussis sample. Using multiple vaccination datasets aided data capture and avoided self-reporting, and has been used previously [38]. Some vaccination administrations might still have been missed.…”