Flu Vaccination Rates Rise for Pregnant Women but Still Fall Short

Pregnant women may be more susceptible to severe illness from influenza infections. Still, despite the benefits and safety of flu vaccination during pregnancy, a new report from the Centers for Disease Control and Prevention (CDC) shows that at best, only half of pregnant women are getting the flu shot.

According to a new study published in the CDC’s Morbidity and Mortality Weekly Report (MMWR), researchers have found that while influenza vaccine coverage during pregnancy has steadily increased in the United States in recent years, the number of pregnant women receiving the flu shot is still well below target goals. These findings coincide with a recent media release from the CDC indicating low influenza vaccination rates overall, across the United States.

The report cites public health recommendations for 2016 that all women who are or may become pregnant received the vaccination. In the 2005-2006 through the 2008-2009 flu seasons, vaccination rates among pregnant women held at a rate of just 17% to 20%. That coverage rate increased to 33% during the 2009-2010 flu season when the novel H1N1 swine flu virus emerged, causing the first global flu outbreak in more than 40 years. A vaccine for H1N1 became available that season as a separate immunization, and the component was added to the following season’s vaccine. During the 2013-2014 flu season, 41% of pregnant women received the flu vaccine, and a recent CDC study found that rate went up to 50% for the 2015-2016 season.

The study was led by researchers at the Birth Defects Study of the Slone Epidemiology Center at Boston University, as part of its surveillance on medications and birth defects. They note that their data covered only 5,318 women who received the flu vaccine during pregnancy over the nine flu seasons between 2005 and 2014. Since their research did not include women who received the flu shot up to six months before becoming pregnant, the percent of pregnant women covered by the flu vaccine may be higher than noted in this study.

Their findings, note the authors, offer data that may help public health officials boost flu vaccine coverage among pregnant women. “Incorporating counseling and education about influenza vaccination during pregnancy and administration of seasonal influenza vaccine into the routine management of pregnant women would offer a potential opportunity to increase influenza vaccination coverage among this vulnerable group and help prevent influenza-associated morbidity and mortality among pregnant women and their infants,” concluded the authors.

During pregnancy, women experience changes to their immune systems, heart, and lungs. An expectant mother’s immunity to viral infections may be altered and in some ways suppressed due to hormonal changes, while lung capacity decreases and heart rate increases. As a result, pregnant women infected with the influenza virus may be more prone serious flu symptoms and have an increased risk of complications such as miscarriage, premature birth, and babies with birth defects and low birth weight.

According to the CDC, receiving a flu shot during pregnancy can protect both a mother and her baby throughout pregnancy as well as for several months after birth, as mothers can pass on important antibodies that protect young infants. The agency has conducted several studies on flu vaccine safety in pregnant women, finding no link between the flu shot and pregnancy complications or adverse fetal outcomes. Additional studies have also found no increased risk of miscarriage, pre-eclampsia, premature delivery, or low birth weight infants for women who received the flu vaccine during pregnancy. A 2014 World Health Organization (WHO) report on the safety of immunization notes the benefits of influenza vaccination for both mothers and newborns, especially when given during the second or third trimester. As such, WHO officials recommend that national immunization policies worldwide include influenza vaccination for pregnant women.