Positive birth outcomes for flu vaccine during pregnancy

An Aussie study has found reassuring evidence of flu vaccine safety during pregnancy, but some mums still have concerns

The cohort study led by the Menzies School of Health Research enrolled 7,126 women who gave birth to a single infant between 2012 and 2014.

In this group there were 2,429 women who had flu vaccine during their pregnancy (34%), while the remainder (66%) did not.

Mean maternal age of participants at birth of infant was 31.7 years, and most mothers who received the flu vaccine did so in the second trimester (51%).

The study published in Vaccine found there were no statisfically significant differences between vaccinated and unvaccinated mothers in relation to weeks’ gestation at birth of the infant: 38.7 versus 38.8 weeks respectively (p=0.051).

Researchers found a non-significant difference of 15g in the point of estimate of birthweight between infants born to vaccinated mothers (3337g) compared with infants born to unvaccinated mothers (3352g). Mean birthweight across the whole cohort was 3347g.

“Our results showed no clinically significant difference 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,” says the lead author, Menzies PhD student Lisa McHugh.

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

“The reason flu vaccination is recommended in pregnancy by the World Health Organization and other expert groups is because pregnant women are at higher risk of severe illness if they do acquire influenza infection when pregnant,” she says.

“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.”

Researchers hope the study results will reassure pregnant women and healthcare providers that vaccination is the best course of action to prevent influenza infection during pregnancy.

Uptake in this cohort is currently lower than it should be, says chief investigator, Menzies research fellow and chair of the Australian Technical Advisory Group on Immunisation, Professor Ross Andrews.

He says the results reveal some concerns prevail surrounding the safety of the flu vaccine during pregnancy.

“Monitoring safety, uptake and effectiveness is critical for any vaccine program but particularly for vaccines given in pregnancy,” says Professor Andrews.

“In our study, only one in three women had a flu vaccine during their pregnancy, despite the recommendations.”

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1 Comment

  1. Ron Batagol

    A very useful study.
    Furthermore, just to reinforce the aspect of any residual concerns that pregnant women may have on this issue, pharmacists and other health advisors need to be aware of the consensus of expert advice on this important health prevention measure, and can assist, by reassuring their pregnant patients/clients that:

    1. WHO recommends seasonal influenza vaccination to pregnant women as the highest priority.
    See http://www.who.int/immunization/newsroom/newsstory_seasonal_influenza_vaccination_pregnancy/en/
    where it also states that :“Children under six months of age can be protected against influenza through vaccination of mothers during pregnancy and vaccination of close contacts to limit transmission of influenza viruses to the young infant”.


    2. In Australia, The Immunise Australia Program,under “Influenza vaccination in children”, at: http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/immunise-influenza in the section ” Questions and Answers for Influenza (flu) immunisation:”, under the heading – “Is it safe for me to get the flu shot if I am pregnant?”,states as follows:

    “Yes. The flu vaccine can be safely given during any stage of pregnancy. Pregnant women are at the increased risk of severe disease of complications from the flu. Immunising against flu during
    pregnancy can not only protect women but provide ongoing protection to a newborn baby for the first six months after birth”.

    It also notes that “Children can begin to be immunised against the flu from six months of age”, and it identifies which specific brands of flu vaccine are registered with the TGA for use in children,
    within specific age groups.
    Ron Batagol,
    Pharmacist and Medicines in Pregnancy Consultant.

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