Maternal influenza vaccination appears to confer benefits to infants, having been associated with a reduced risk of infant influenza hospitalizations within a tropical setting, as shown in a retrospective study from Singapore.
In a local cohort of 221,185 infants (51.4 percent male, 64.4 percent Chinese) followed for an average of 182 days from birth, the incidence of influenza hospitalizations was lower among infants born to mothers who received a flu vaccine during pregnancy vs those born to unvaccinated mothers (0.69 vs 1.17 per 100,00 person-days; adjusted hazard ratio, 0.59, 95 percent confidence interval [CI], 0.45–0.77). [JAMA Netw Open 2026;9:e2628389]
Vaccine effectiveness against influenza hospitalization in infants was 41 percent (95 percent CI, 23–55).
“Influenza vaccination for the mother remained protective against influenza hospitalization in the infant, regardless of whichever trimester or season vaccination was administered in,” said Dr Ian Wee, corresponding author of the study and also an infectious diseases specialist at Singapore General Hospital, in an email to MIMS.
Specifically, vaccine effectiveness estimates were 41 percent for prior-season and current season maternal vaccination and 52 percent, 37 percent, and 41 percent for first, second, and third trimester maternal vaccination, respectively.
“Therefore, for clinicians seeing unvaccinated pregnant individuals, any time is a good time to recommend influenza vaccination. There is no ‘wrong’ time,” Wee added.
Low uptake
In the cohort, maternal influenza vaccine uptake was low. Only 25.9 percent of infants were born to vaccinated mothers despite widespread availability of subsidized vaccination in primary care and extensive evidence supporting influenza vaccine safety in pregnancy, as Wee and colleagues pointed out in their paper.
“Vaccine hesitancy is complex,” Wee told MIMS.
To address vaccine hesitancy in clinical practice, Wee urged clinicians to reassure pregnant mothers about the safety of influenza vaccination during pregnancy. “There is extensive data supporting foetal safety of maternal influenza vaccination, and flu vaccination protects not just the pregnant mother but also the infant. This is especially crucial in early infancy, as children only start receiving influenza vaccination from 6 months onwards,” he said.
Wee and colleagues also noted in their paper that year-round provision of influenza vaccination for pregnant individuals can facilitate same-day pairing of maternal influenza immunization with other recommended vaccines to maximize uptake, an approach supported by safety data for administration of influenza vaccines with additional vaccines in pregnancy. [JAMA Netw Open 2026;9:e267551]
For the retrospective study, infants were followed up from birth until an influenza hospitalization, 6 months of age, or death, whichever occurred first. The mean follow-up time was 181.9 days for infants born to vaccinated mothers and 182.3 days for infants born to unvaccinated mothers.
Limitations included the possible underestimation of the frequency of severe influenza, given that influenza may present non-specifically in infancy, and the lack of subtype data for influenza hospitalizations.