For years, pregnant women have been urged to get the annual flu shot because they run a high risk of medical complications if they do get sick. Now, there is fresh evidence the vaccine can help safeguard their newborns against influenza, too.
A recent study shows that infants whose mothers received the flu shot while pregnant are significantly less likely to get flu or be admitted to hospital with a respiratory illness in the first six months of life.
The findings are based on 1,160 infants and their mothers who where followed for three flu seasons.
"On average, there was about a 40-per-cent degree of protection among those infants who were born to mothers who were immunized compared to those who had been born to moms who hadn't been immunized," said the senior researcher, Katherine O'Brien of Johns Hopkins Bloomberg School of Public Health in Baltimore.
Dr. O'Brien noted that there is no point giving a flu shot to children under six months of age because their immature immune systems aren't capable of producing enough antibodies to fight the flu.
However, the study demonstrated that children can get sufficient antibody protection from their vaccinated mothers.
There is a transfer of antibodies across the placenta while the infant is still in the womb, said Dr. O'Brien. After birth, the infant receives a continuing supply of antibodies through breastfeeding. Blood tests confirmed the children of vaccinated mothers had antibodies to the flu strains contained in the annual flu shot. The study was published in Archives of Pediatrics and Adolescent Medicine.