Pregnant women who receive influenza vaccine during pregnancy are at 40% reduced risk of flu hospitalization as compared to women who are not vaccinated during pregnancy reports the results of a Center for Disease Control (CDC) co-authored study published online October 11, 2018, in the journal Clinical Infectious Diseases.
“Expecting mothers face a number of threats to their health and the health of their baby during pregnancy, and getting the flu is one of them,” explains Allison Naleway, Ph.D., a study co-author from the Kaiser Permanente Center for Health Research. “This study’s findings underscore the fact that there is a simple, yet impactful way to reduce the possibility of complications from flu during pregnancy: get a flu shot.
In this retrospective cohort study, the researchers gathered data from more than 2 million pregnancies for 6 years (2010-2016), across cross 5 regions in 4 countries through the Pregnancy Influenza Vaccine Effectiveness Network (PREVENT), which consists of healthcare systems with integrated laboratory, medical, and vaccination records. Nearly 85% of pregnancies were ongoing during the flu season making it highly likely that pregnant women were exposed to flu at some point during their pregnancy.
Key study findings include:
With nearly 84% pregnancies overlapping the influenza season, the risk of influenza virus infection is a real threat during pregnancy.
Influenza vaccine reduced the risk of moderate to severe laboratory-confirmed influenza (LCI) infection during pregnancy.
Flu vaccine was equally protective in women with other medical co-morbidities like asthma and diabetes, which puts them at higher risk of other medical complications.
Flu vaccine offers equal protection during all the three trimesters.
“Our study found that flu vaccination worked equally well for women in any trimester and even reduced the risk of being sick with influenza during delivery,” adds Mark Thompson, Ph.D., a study co-author and epidemiologist with CDC’s Influenza Division.
In addition to protecting the mothers from flu while being pregnant, influenza vaccine offers protection to the newborn for several months after birth, till they are old enough to get vaccinated.

