Study: flu vaccine safe during pregnancy

An Australia-wide study published in the international journal “Vaccine” has provided evidence of the safety of influenza vaccination during pregnancy.

Led by Menzies School of Health Research, the collaborative study involved 7126 women over three consecutive years to assess the safety of receiving an influenza vaccination during any trimester of pregnancy with respect to preterm births and infant birthweight.

The study found 2429 women had a flu vaccine during their pregnancy, with most receiving the vaccination during their second trimester; the remainder did not vaccinate against the flu.

Lead author and Menzies PhD candidate, Lisa McHugh said the study found women who had an influenza vaccine in pregnancy were not at increased risk of having a preterm or low birthweight baby compared with those who were not vaccinated.

“Our results showed no clinically significant differences in infant birthweight or gestational age at birth of the infant for women who received an influenza vaccination during any trimester of pregnancy compared with unvaccinated mothers,” Ms McHugh said.

The findings support the current recommendation in Australia to vaccinate all women who are pregnant during the influenza season.

Ms McHugh said the reason flu vaccination was recommended in pregnancy by the World Health Organization and other expert groups was because pregnant women were at higher risk of severe illness if they did acquire influenza infection when pregnant.

“This is due to reduced immunity or if the pregnant woman has a co-morbidity or risk factor such as diabetes or a history of respiratory illness like asthma or bronchitis,” she said.

Chief investigator and Chair of the Australian Technical Advisory Group on Immunisation, Menzies’ Professor Ross Andrews said the study showed there was still some concern by pregnant mothers around the safety of the flu vaccine. 

“Monitoring safety, uptake and effectiveness is critical for any vaccine program, but particularly for vaccines given in pregnancy,” Professor Andrews said. The study indicates that only one in three women had a flu vaccine during their pregnancy, despite the recommendations.”

The study was funded by the National Health and Medical Research Council.