Infants with vaccinated moms less likely to get flu

Babies are much less likely to get the flu during their first six months of life, if their moms get flu vaccinations while pregnant, a US study said.

Infants six months and younger, whose mothers were vaccinated when pregnant, had a 70 percent reduction in laboratory-confirmed flu cases and an 80 percent reduction in flu-related hospitalisations, compared with babies whose moms were not immunised, according to the study published online in the US journal Pediatrics on Tuesday.

"Babies cannot be immunised during their first six months, so they must rely on others for protection from the flu during that time," Xinhua news agency quoted lead author Julie Shakib, assistant professor of pediatrics at the University of Utah School of Medicine, as saying.

"When pregnant women get the flu vaccine there are clear benefits for their infants."

Shakib and colleagues examined more than 245,000 de-identified health records of pregnant women and more than 249,000 infant records for nine flu seasons from December 2005 through March 2014.

About 10 percent of the women -- 23,383 -- reported being vaccinated while pregnant compared with 222,003 who said they were not vaccinated, they found.

Over the study's course, laboratory-confirmed flu cases were reported among 658 infants. Of these cases, 638, or 97 percent, occurred in babies whose moms were not immunised.

A total of 151 of the 658 infants were hospitalised, with 148 being born to non-immunised pregnant women.

In order to confirm that the benefits observed in infants born to mothers who received flu vaccinations were not related to chance, the researchers also examined health records for the incidence of respiratory syncytial virus (RSV), a respiratory infection that also occurs in infants and young children during the winter months.

The analysis found that the vaccine had no effect on the incidence of RSV among infants, strengthening the findings that the benefits seen in the infants were actually due to the flu vaccine their mothers received.

The results led the researchers to declare that the need for getting more pregnant women immunised is a public health priority.

"We just really hope more pregnant women get the vaccine," Shakib said. "That's the take-home message of the study."