MATERNAL influenza vaccination during pregnancy was linked with a reduction in the number of influenza-associated visits to the emergency department in infants aged younger than 6 months. Led by Leila C. Sahni, Baylor College of Medicine and Texas Children’s Hospital, Houston, USA, the research underscores the protective benefits for infants in this age group, who are ineligible for licensed influenza vaccines.
The study included a cohort of 3,764 infants aged younger than 6 months who were either seen in the emergency department or had been hospitalised for an acute respiratory illness within the New Vaccine Surveillance Network from the 2016–2017 to the 2019–2020 influenza seasons. Researchers also accessed medical records, immunisations systems, and asked parents to report on maternal vaccination status.
Results found that of the 3,541 infants in the control group and the 223 infants with influenza, 53% were born to mothers who had received an influenza vaccination during their pregnancy. Maternal vaccination was shown to be 34% effective overall (95% confidence interval [CI]: 12–50%), 39% effective against influenza-associated hospitalisations (95% CI: 12–58%), and 19% effective against emergency department visits. Authors of the study also observed that in infants aged younger than 3 months, overall effectiveness was 53% (95% CI: 30–68%). In mothers who were vaccinated during the first or second trimesters, effectiveness was 17% (95% CI: 15–40%), and in mothers who were vaccinated during their final trimester, the effectiveness was 52% (95% CI: 30–68%).
The researchers involved in the study noted that although the benefits of maternal influenza vaccination have been well demonstrated for both mothers and infants, uptake of such vaccination is still sub-optimal. They concluded: “While continued efforts are needed to determine optimal timing, clinicians should continue to offer influenza vaccination at any time during pregnancy to protect both the pregnant person and infant.”
