Maternal vaccination prevents flu-associated hospitalizations among infants
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Maternal influenza vaccination was around 65% effective at preventing influenza-associated hospitalizations among infants when the viruses matched what was in the vaccine, according to a study published in Open Forum Infectious Diseases.
“In a randomized control trial, we had previously shown that influenza vaccination during pregnancy protected the mothers and their infants against influenza disease. However, in the trial, most of the influenza infections were mild and we didn’t evaluate the impact of this strategy on the prevention of influenza-associated hospitalizations,” Marta C. Nunes, PhD, associate professor at the University of the Witwatersrand’s vaccines and infectious diseases analytics research unit, told Healio.
She added that this is important because “pregnant women experience higher rates of influenza-associated hospitalization than nonpregnant women,” and in infants, influenza infection is also associated with increased rates of hospitalization.
Nunes and colleagues assessed the effect of maternal vaccination in HIV-uninfected women and women living with HIV to prevent influenza-associated hospitalizations of infants aged younger than 6 months, as well as among the women.
According to the study, from 2015 through 2018, influenza vaccination campaigns targeting pregnant women were augmented at selected antenatal clinics in two South African provinces. These were paired with ongoing prospective hospital-based surveillance for acute respiratory or febrile illness in young infants and cardiorespiratory illness among pregnant or postpartum women.
Overall, 71 influenza-positive and 371 influenza-negative infants were included in the analysis. The mothers of 26.8% of influenza-positive infants were vaccinated during pregnancy compared with 35.6% of influenza-negative infants, corresponding to an adjusted vaccination effectiveness (aVE) of 29% (95% CI, –33.6-62.3), although when limited to vaccine-matched strains, aVE was 65.2% (95% CI, 11.7-86.3).
According to the study, for maternal hospitalizations, 56 influenza-positive and 345 influenza-negative women were included in the analysis, with 28.6% of influenza-positive women being vaccinated compared with 38.3% of influenza-negatives, showing an aVE of 46.9% (95% CI, –2.8 to 72.5). Analysis focused on HIV-uninfected women resulted in 82.8% aVE (95% CI, 40.7-95), whereas no significant aVE was detected among women with HIV (–32.5%; 95% CI, –208.7 to 43.1)
“Pregnant women should be vaccinated with inactivated influenza vaccine to protect themselves and their infants, not only against mild disease but also against hospitalization,” Nunes concluded.
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