Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In a retrospective cohort study, children born to mothers vaccinated with the Tdap vaccine during pregnancy did not have increased rates of immune-related outcomes, sensory disorders, or neoplasms.

2. Rates of upper respiratory infections, gastrointestinal infections, and urgent care/inpatient health service use were reduced in children of mothers who were vaccinated with Tdap.

Evidence Rating Level: 2 (Good)

Study Rundown:

Maternal vaccination with the tetanus, diphtheria, and acellular pertussis vaccine (Tdap) is recommended during pregnancy to decrease the risk of severe pertussis infection among infants. Evidence supports the safety of the Tdap vaccine for neonatal and fetal outcomes, however there is limited research regarding its effects on long-term childhood health outcomes. This study evaluated data collected through administrative databases of infants followed for a 6-year period after birth. Childhood health outcomes included immune-related outcomes (i.e., infections and asthma), sensory disorders (i.e., hearing and vision loss), and neoplasms. Non-specific health outcomes were also assessed, which included urgent and inpatient health services use. There was no association between maternal Tdap vaccination and adverse health outcomes in childhood. A small but statistically significant inverse association was observed between maternal Tdap and childhood upper respiratory infections, gastrointestinal infections, urgent care visits, and hospitalizations. Although limited in its ability to account for confounders due to the retrospective design, this study’s results can assure parents that the Tdap vaccine during pregnancy is not associated with childhood adverse outcomes.

In-Depth [retrospective cohort]:

This population-based retrospective cohort study included 625,643 maternal-child pairs who were eligible for health care in Ontario, Canada. A total of 12,045 infants born to mothers between 2012-2017 were immunized with Tdap during pregnancy (1.9%). There were 60,225 unexposed infants matched to immunized infants at a ratio of 5:1. Infants were matched based on measures of maternal health and socioeconomic factors. There was no significant increase in adverse health outcomes in children born to mothers immunized with Tdap. There was an inverse association with upper respiratory infections (aIRR 0.94, 95% CI: 0.90-0.99), gastrointestinal infections (aIRR 0.85, 95% CI: 0.79-0.91) and urgent and inpatient health service use (aIRR 0.93, 95% CI: 0.91-0.96).

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