Pregnant women should be encouraged to take flu vaccines, according to researchers at the University of Western Australia, who demonstrated that flu vaccines reduce the risk of hospital stays due to respiratory infections, such as pneumonia, by more than half.
The research study, “Effectiveness of seasonal trivalent influenza vaccination against hospital-attended acute respiratory infections in pregnant women: A retrospective cohort study,” was published in the journal Vaccine.
Among pregnant women, almost a third of hospital admissions for respiratory infections are for influenza, according to Annette Regan, project officer at the Western Australia Health Department and the researcher who led the study as part of her Ph.D. thesis.
“They are more than five times as likely as non-pregnant women in the same age group to end up in hospital [when they get the flu],” Regan said in a press release.
Also, the mortality rates due to respiratory infections are highest in pregnant women than in any other group of patients. “They are more likely to get these really, really bad infections, and that can be bad not only for the Mum but also for the baby,” Regan said.
In the study, Regan and colleagues compared the outcomes of 3,007 vaccinated pregnant women with those of 31,694 unvaccinated pregnant women. Women who got the vaccine received it during their pregnancy: 17.5 percent in the first trimester, 62.1 percent in the second trimester, and 20.3 percent in the last trimester.
Pregnant women who did not get the flu vaccine were found to be three times more likely to visit a hospital emergency department for an acute respiratory infection, including influenza, pneumonia, or bronchitis.
Although only 8.7 percent of women were vaccinated in this study, Regan said that in the last three years the immunization rates have greatly improved. “We’ve just come up with estimates for 2015 … and we were really pleased to see that it’s increased to 60 percent,” she said.
“Obviously we’d like to see it get a lot higher than that because of all these benefits that we’re seeing associated with vaccination — we’d love to see almost 100 percent of pregnant women get vaccinated,” Regan added.
This is the first population-based study demonstrating that flu vaccines can have a protective effect in preventing hospital admissions due to respiratory infections in pregnant women. It is noteworthy that the flu vaccine is safe in any pregnancy trimester.
Scientists also believe that some antibodies can cross the placenta and protect the baby in its first six months of life, supporting the theory that pregnant women should be encouraged by their doctors to get vaccinated.
“Flu season is imminent; we know it’s going to start in the next couple of weeks,” Regan said. “This would be a good time if you haven’t had a flu vaccine yet to book in with your [general practitioner] or your clinic or your obstetrician.”