Immunization Update
Maria G. Tanzi, PharmD
Maternal influenza vaccination given during pregnancy did not adversely affect childhood health outcomes among offspring, according to data published in the June 8 issue of JAMA.
The retrospective analysis of data from over 28,000 children—10,227 of which were born to women who received seasonal influenza vaccination during pregnancy—showed that the risk of immune-related health outcomes, non-immune-related outcomes, or nonspecific health outcomes were not significantly affected by maternal vaccination.
“Benefits of vaccination have been well documented, with studies showing immunogenicity in pregnant women, transplacental antibody transfer to the infant, and clinical efficacy and effectiveness against influenza-associated illness in mother and infants,” wrote Eduardo Azziz-Baumgartner, MD, and CDC colleagues in an accompanying editorial.
Low rates a concern
CDC estimates that only about half of pregnant women get vaccinated against influenza annually, and too many women remain unprotected. During the 2016–17 influenza season, for instance, 53.6% of women reported receiving the influenza vaccine.
Although these numbers were slightly higher than previous years, it is far short of the 80% goal that was set for 2020.
In the JAMA study, only 36% of expectant mothers received the influenza vaccine. Researchers analyzed a birth registry linked with health administrative data from all live births in Nova Scotia, Canada, between October 1, 2010, and March 31, 2014. Babies were followed through March 31, 2016.
In the accompanying editorial, Azziz-Baumgartner and colleagues said that the low rates of annual influenza cases during the 2020–21 northern and southern hemisphere influenza seasons might have specific implications for infants in the 2021–22 influenza seasons.
They write, “A potential implication of markedly reduced influenza circulation and low incidence of infections is that pregnant women might not have antibodies that could protect their infants from increased risk of infection and severe illness during the next influenza epidemic. Efforts are needed now to encourage maternal influenza vaccination worldwide and to act on the compelling efficacy and safety data.”
Counseling pearls
Health care practitioners should educate women who are pregnant about the importance of getting the influenza vaccine to protect themselves and their baby. Inform them that influenza can cause serious illness, but the risk is especially high in pregnant women because of changes in immune, heart, and lung function during pregnancy.
Pharmacists and other health care practitioners should tell pregnant patients that the vaccine can be given at any time during their pregnancy, although data are limited to the first trimester.
Women should also understand the concept of antibodies. Pharmacists can let pregnant patients know that their bodies will start to make antibodies in about 2 weeks after the influenza vaccine is administered. These antibodies are passed on to the developing baby and can help protect the baby for several months after birth. They can also be passed to the infant through breast milk.
Pregnant patients should know that the influenza vaccine cannot be given to babies less than 6 months of age, so the protection received from the mother is beneficial.
Since some women will be concerned about the safety of the vaccine during pregnancy, pharmacists can explain to them that millions of pregnant women have received the influenza vaccine in the past and these vaccines have a good safety record.
They should also be educated on common adverse events that can occur at the injection site, such as soreness, tenderness, redness and/or swelling, and other potential adverse effects such as headache, muscle aches, fever, nausea, or tiredness.
If women fail to receive the influenza vaccine during pregnancy, they should still be encouraged to get vaccinated after they deliver their baby to help prevent the spread of the disease. Others who care for the baby should also be encouraged to get vaccinated to further protect the child.