1. No significant association was identified between maternal intrapartum vaccination with the influenza or tetanus, diphtheria, and acellular pertussis (Tdap) vaccine and infant hospitalization or mortality.
2. Infants hospitalized for respiratory reasons were significantly less likely to be born to mothers who had received the Tdap vaccine when compared to case-matched controls.
Evidence Rating Level: 3 (Average)
Study Rundown: Though both the influenza and Tdap vaccines are recommended for women during pregnancy, few studies have explored any possible association between maternal vaccination and infant hospitalization or mortality beyond the neonatal period. Using data from 5 different healthcare systems, investigators found no significant association between maternal vaccination with either the influenza or Tdap vaccines and infant hospitalization or mortality in infants up to 6 months of age when compared to case-matched controls. Simultaneously, the odds of a mother having received a Tdap vaccine were significantly lower in those infants hospitalized for respiratory reasons. Overall, infants who were hospitalized were more likely to be born to women who had pregnancy complications and were less likely to have been delivered by cesarean section. This study is limited as it only captures an insured and, thus, possibly healthier population. Still, the results of this study validate the already-established understanding of vaccine safety and, furthermore, support the value of maternal vaccination in preventing neonatal disease.
In-Depth [case-control study]: Researchers completed a case-control study utilizing data from 5 Vaccine Safety Datalink (VSD) healthcare systems geographically dispersed across the United States. VSD allows for data from mother and child to be link for analysis, and the database included 500 447 infants born between January 1, 2004 and January 30, 2014. A total of 87 413 infants were excluded for various reasons—including multiples, no prenatal care, or live vaccines given in pregnancy—leaving 413 034 for analysis. Of those included, 25 222 infants were hospitalized within the first 6 months of life, 157 infants died within the first 6 months of life, and the remaining 387 670 were used as controls. Of those infants hospitalized, 4644 were hospitalized for respiratory reasons. There was no significant association between maternal vaccination with either or both of the influenza or Tdap vaccine and infant hospitalization (both vaccines, adjusted OR = 0.97 (0.90-1.05)) or death (both vaccines, aOR = 0.32 (0.08-1.24)). There was a lower likelihood of maternal vaccination with the Tdap vaccine in infants hospitalized for respiratory reasons (aOR = 0.79 (0.67-0.94), p=.007).
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