The effectiveness of the influenza (flu) vaccine for pregnant women is determined by the trimester the woman is in when she receives the shot. The findings were presented at the Society for Maternal-Fetal Medicine’s annual meeting, The Pregnancy Meeting™. The Centers for Disease Control and Prevention (CDC) recommends that all pregnant women receive the flu shot – unless they got one within the last year. The CDC reported, “Flu is more likely to cause severe illness in pregnant women than in healthy women who are not pregnant.”
The researchers of the study found that T-follicular helper cell response to the flu vaccine is greatest during the first trimester.
The study involved 36 pregnant women during the flu season between 2012 and 2014. The women were administered inactivated influenza vaccines, and blood samples were taken prior to vaccination and 14 days after vaccination.
Presenter of the study Emily Patel said, “The study results suggest that immunological changes during pregnancy may affect the response to the vaccination. Future studies will lead to a better understanding of vaccine immunology, and how pregnant women respond to antigen exposure through the course of their pregnancy.”