According to researchers in Canada, only 36% of pregnant women received the flu shot over four flu seasons in Nova Scotia. Of those who don’t get the vaccination, safety concerns are a major factor. But the Canadian study, published in JAMA, found that moms who got the vaccine during pregnancy didn’t adversely affect their children. Pregnant women aren’t more likely to get infected with flu, but they are at a higher risk for serious illness and complications if they get flu during pregnancy. According to the Centers for Disease Control and Prevention (CDC), this is due to changes in the immune system, heart, and lungs during pregnancy. The CDC also warns that flu may be harmful for the developing baby—a common symptom of flu is fever, which may be associated with adverse outcomes like neural tube defects. A 2018 study showed that getting a flu shot reduced a pregnant woman’s risk of being hospitalized with flu by an average of 40%.
Details of the New Study
The research team, led by Deshayne Fell, PhD, MSc, an associate professor of epidemiology in the Faculty of Medicine at the University of Ottawa, followed over 28,000 children from birth up to an average age of 3.5 years. The results suggest that maternal influenza vaccination during pregnancy was not associated with immune-related health conditions, such as asthma, ear infections or other types of infection, or non-immune-related health problems like neoplasms or sensory impairment. Furthermore, there was no increase in nonspecific health needs, such as emergency department visits and hospitalizations. “Although we advise all pregnant women to receive a flu shot each year, many do not,” says Dr. Fell. “Since we know that flu vaccination during pregnancy protects not only pregnant individuals, but also provides protection to the babies after they are born (for about the first four months or so), it is an important public health measure.” Dr. Fell adds that until a few years ago, there were not many formal studies that specifically evaluated longer-term safety of the flu vaccine during pregnancy. “We did this study to be able to provide evidence that can help inform decision-making by pregnant people, their care providers, and public health officials,” she explains. It’s important to note that flu vaccine uptake is higher in parts of the U.S. and other countries, such as Australia, than in Canada, where the study was carried out. In 2019, the CDC reported that 54% of pregnant women in the U.S. got the flu shot before or during pregnancy.
A Combination of Concerns
“In general, I think lower uptake is due to a combination of concerns about safety, lack of concern about getting the flu itself, and lack of convenience for pregnant people to get the flu shot,” says Dr. Fell. “Other research has shown that when the flu shot is recommended by a trusted health care provider and offered in the prenatal care setting, uptake is quite high. But unfortunately that doesn’t always happen in a way that is convenient for pregnant people to access.” G. Thomas Ruiz, MD, OB/GYN at MemorialCare Orange Coast Medical Center in Fountain Valley, California, says that in his experience, it’s common for pregnant women to refuse optional treatments such as the flu vaccine. “There is a pervasive belief that anything you give mom, may harm the baby—for example, affecting the baby’s development in utero,” he says. Dr. Ruiz’s case for getting the flu shot during pregnancy is twofold. “First, I let every patient know the vaccine material does not get to the baby,” he says “The vaccine causes the body to produce protective antibodies, which do cross the placenta, but they’re not harmful.” Secondly, Dr. Ruiz tells his patients that a pregnant flu patient gets much sicker than a non-pregnant flu patient. “I go into great detail so they can make an informed decision on what is best for them and their unborn baby,” he adds. “Pregnant women need a flu shot because they get so much sicker than the general population. Pregnant patients are more likely to get flu-related pneumonia and sequelae of pneumonias, which is why I strongly recommend that they receive the flu shot.”
