Maternal influenza, Tdap vaccinations not tied to infant mortality
Influenza and acellular pertussis vaccinations during pregnancy were not associated with hospitalization or death of infants in the first 6 months of life, according to recently published study results in Pediatrics.
“In our study of maternal influenza and [acellular pertussis (Tdap)] vaccines, we found no increased risk of infant all-cause hospitalizations, hospitalization from respiratory causes, or all-cause mortality in the first 6 months of life,” Lakshmi Sukumaran, MD, MPH, of the Immunization Safety Office, CDC, and colleagues wrote. “… Our findings are similar to other studies that have evaluated infant mortality and morbidity after maternal vaccination in pregnancy, most of which have evaluated the safety of adjuvanted H1N1 influenza-containing vaccines.”
“Our findings are also consistent with studies in which researchers have evaluated infant mortality and morbidity after Tdap vaccination in pregnancy,” the researchers added.
Sukumaran and colleagues used the Vaccine Safety Datalink, a collaboration between the CDC and eight integrated health-care sites with data on vaccinations and health care for about 10 million people per year. Data on pregnant women from five VSD sites, including 90% of the VSD population, were used. Singleton live birth pregnancies between 2004 and 2014 were included.
Infants with hospitalization or deaths within the first 6 months of life were outcomes. Case patients were matched with controls based on VSD site, birth month and year (within 1 month) and gestational age groups of later preterm (34-36 weeks), term (37-41 weeks) and post-term (42-44 weeks).
Maternal exposure to influenza or Tdap vaccines, or both, during pregnancy were estimated using conditional logistic regression.
There were 413,034 infants in the study, including 25,222 who had one or more hospitalizations and 157 infants who died. There were 4,644 infants (18.4%) hospitalized for respiratory cause, including 105 (2.2%) who had an influenza ICD-9 code (487, 488) and 137 infants (3%) who had a pertussis ICD-9 code (033.0, 033.9). Although 14 infants died of respiratory causes, none of the deaths were attributed to influenza or pertussis infections based on review of laboratory and medical records.
Unknown causes (32%), sudden infant death syndrome (21%) and certain conditions originating in the perinatal period (17%) were the most common causes of death.
Infant hospitalization was not associated with maternal influenza vaccination (adjusted OR = 1.00; 95% CI, 0.96-1.04) or Tdap vaccinations (aOR = 0.94; 95% CI, 0.88-1.01). Infant mortality also was found not to be associated with maternal influenza vaccination (aOR = 0.96; 95% CI, 0.54-01.69) or Tdap vaccination (aOR = 0.44; 95% CI, 0.17-1.13).
“This is the first study in which infant hospitalizations and mortality in the first 6 months of life after maternal influenza vaccine and Tdap vaccines are evaluated,” the researchers concluded. “In this large case-control study, we found no increased risk of infant hospitalization and death after vaccination in pregnancy. Our findings support the safety of influenza and pertussis vaccinations during pregnancy for infants of vaccinated mothers.”
Disclosures: The authors report no relevant financial disclosures.