Infant Hospitalizations and Mortality After Maternal Vaccination

Abstract

Background: The Advisory Committee on Immunization Practices currently recommends pregnant women receive influenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines. There are limited studies of the long-term safety in infants for vaccines administered during pregnancy. We evaluate whether maternal receipt of influenza and Tdap vaccines increases the risk of infant hospitalization or death in the first 6 months of life.

Methods: We included singleton, live birth pregnancies in the Vaccine Safety Datalink between 2004 and 2014. Outcomes were infant hospitalizations and mortality in the first 6 months of life. We performed a case-control study matching case patients and controls 1:1 and used conditional logistic regression to estimate odds ratios for maternal exposure to influenza and/or Tdap vaccines in pregnancy.

Results: There were 413 034 live births in our population. Of these, 25 222 infants had hospitalizations and 157 infants died in the first 6 months of life. We found no association between infant hospitalization and maternal influenza (adjusted odds ratio: 1.00; 95% confidence interval [CI]: 0.96-1.04) or Tdap (adjusted odds ratio: 0.94; 95% CI: 0.88-1.01) vaccinations. We found no association between infant mortality and maternal influenza (adjusted odds ratio: 0.96; 95% CI: 0.54-1.69) or Tdap (adjusted odds ratio: 0.44; 95% CI: 0.17-1.13) vaccinations.

Conclusions: We found no association between vaccination during pregnancy and risk of infant hospitalization or death in the first 6 months of life. These findings support the safety of current recommendations for influenza and Tdap vaccination during pregnancy.

FIGURE 1

Study population of infants with hospitalization or death in the first 6 months of life in the VSD, 2004–2014. ^a Infants with continuous enrollment in the VSD until 6 months of age or until the time of death whose mothers were enrolled for the duration of their pregnancy. ^b Fifteen infants were hospitalization and death case patients. ^c Defined as ICD-9 codes: 033, 460–488, 491–496, 510–519. ^d Defined as ICD-10 codes: A37, J00–J99. ^e Positive influenza A or B antigen, viral culture, PCR, or direct fluorescent antibody test results within 14 days of hospitalization. ^f Positive B pertussis PCR or culture test results within 14 days of hospitalization.

FIGURE 2

Rates of maternal influenza and Tdap vaccination, infant hospitalization, and infant mortality in the VSD, 2004–2013.