Maternal influenza vaccination during pregnancy effectively reduces influenza risk for infants younger than 6 months, especially when combined with breastfeeding. These study results were presented at IDWeek 2023, held from October 11 to 15, in Boston, Massachusetts.
Infants are not eligible for influenza vaccination despite being at increased risk for influenza infection and influenza-related complications. However, some protection against influenza infection may be conferred via maternal vaccination during pregnancy and subsequent breastfeeding. Although evidence suggests breastfeeding allows for the passage of vaccine-specific influenza antibodies from mother to infant, it remains unclear whether there is a combined effect of maternal influenza vaccination plus breastfeeding on influenza burden in infants.
To bridge this knowledge gap, researchers at the University of Pittsburg in Pennsylvania conducted a retrospective cohort study. The analysis included infants (n=44,132) born between 2012 and 2019 and their mothers (n=44,132). The primary outcome was the occurrence of laboratory-confirmed influenza infection among infants prior to 6 months of age. Influenza occurrence was evaluated on the basis of maternal vaccination during pregnancy and breastfeeding status at 3 months following delivery. The researchers assessed outcomes via unadjusted and adjusted logistic regression, following stepwise regression for important covariates (P <.15).
Among the mother-infant pairs included in the analysis, 141 (0.3%) infants developed laboratory-confirmed influenza infection. Further analysis indicated that approximately half of the mothers (51%) were vaccinated against influenza infection during pregnancy and approximately half of the infants (54%) were either partially or exclusively breastfed at 3 months of age.
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Increasing the administration and acceptance of MII in pregnancy and improving sustained breastfeeding rates may help reduce the burden of infant influenza.
Maternal vaccination during pregnancy was associated with some protection against influenza infection in infants (adjusted odds ratio [aOR], 0.63; 95% CI, 0.39-1.01). However, breastfeeding alone was not associated with significant protection against influenza infection (aOR, 0.77; 95% CI, 0.51-1.16) when compared with lack of both breastfeeding and maternal influenza vaccination.
Of note, maternal influenza vaccination during pregnancy in combination with breastfeeding was associated with significant protection against influenza infection in infants (aOR, 0.40; 95% CI, 0.25-0.66).
According to the researchers, “Increasing the administration and acceptance of MII [maternal influenza immunization] in pregnancy and improving sustained breastfeeding rates may help reduce the burden of infant influenza.”
This article originally appeared on Infectious Disease Advisor.
References:
Rick A-M, D’Agostino H, Liu H, Williams JV, Balasubramani GK, Martin JM. Protective effects of maternal influenza vaccine during pregnancy and breastfeeding on risk of infant influenza. Presented at: IDWeek 2023; October 11-15; Boston, MA. Poster 1012.
