Public Release: 

Effectiveness of influenza vaccine for pregnant women may differ by trimester

Society for Maternal-Fetal Medicine

ATLANTA (Feb. 1, 2016)--In a study to be presented on Feb. 5 in an oral concurrent session at 1:15 p.m. EST, at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting™, in Atlanta, researchers will present findings from a study titled, T-follicular helper (Thf) cell expansion varies by trimester after influenza vaccination in pregnancy.

The Centers for Disease Control recommends that all pregnant women get a flu shot, unless they have already been vaccinated over the past year. Cautioning that "Flu is more likely to cause severe illness in pregnant women than in healthy women who are not pregnant," the CDC website recommends that pregnant women may safely get the shot during any trimester.

In the study to be presented, researchers found that the T-follicular helper cell response to vaccination is greatest during the first trimester of pregnancy. Vaccine immunology is poorly understood in pregnancy and Tfh cell expansion has been shown to be a predictor of response to influenza vaccination outside of pregnancy.

The researchers studied 36 pregnant women during flu season in 2012 to 2014. They administered inactivated influenza vaccine and blood samples were collected pre-vaccination and 14 days later. The influenza specific T-follicular helper cell response varied based on trimester of pregnancy in which the vaccine was given.

"The study results suggest that immunological changes during pregnancy may affect the response to the vaccination," stated Emily Patel, M.D. with Duke University. Dr. Patel is one of the researchers and the presenter of the study. "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," added Patel.

###

A copy of the abstract is available at http://www.smfmnewsroom.org and below. For interviews please contact Vicki Bendure at Vicki@bendurepr.com 202-374-9259 (cell).

The Society for Maternal-Fetal Medicine (est. 1977) is the premiere membership organization for obstetricians/gynecologists who have additional formal education and training in maternal-fetal medicine. The society is devoted to reducing high-risk pregnancy complications by sharing expertise through continuing education to its 2,000 members on the latest pregnancy assessment and treatment methods. It also serves as an advocate for improving public policy, and expanding research funding and opportunities for maternal-fetal medicine. The group hosts an annual meeting in which groundbreaking new ideas and research in the area of maternal-fetal medicine are shared and discussed. For more information visit http://www.smfm.org.

Abstract 80: T-follicular helper (Tfh) cell expansion varies by trimester after influenza vaccination in pregnancy

Authors: Emily Patel1, Chad Grotegut1, R. Phillips Heine1, Janet Staats1, Brian Antczak1, Kristin Weaver1, Kent Weinhold1, Geeta Swamy1
University, Durham, NC

Objective: Vaccine immunology is poorly understood in pregnancy. Tfh cell expansion has been shown to be a predictor of response to influenza vaccination outside of pregnancy. Our objective was to determine if Tfh cell expansion after vaccination changes based on trimester of pregnancy.

Study Design: Inactivated Influenza Vaccine (IIV) was administered during the 2012-2014 influenza seasons to 36 pregnant women. Blood samples were collected pre-vaccination and 14 days later. Peripheral blood mononuclear cells (PBMC) were isolated at each time point. Frequency and phenotype of influenza specific T-follicular helper cells (CD4+, CXCR5+, IL21+) was measured using polychromatic flow cytometry. Frequencies were compared using Wilcoxon signed rank test.

Results: The influenza specific T-follicular helper cell response varied based on trimester of pregnancy in which the vaccine was given. There was a significant expansion of Tfh cells after vaccination among women in the first trimester (p=0.036) but there was not a significant expansion after vaccination in either the second or third trimesters (p=0.091 and 0.347 respectively).

Conclusion: The Tfh cell response to vaccination is greatest during the first trimester of pregnancy. These results suggest that immunologic changes that occur during pregnancy may affect response to vaccination. Future work in this area will lead to a better understanding of vaccine immunology and how pregnant women respond to antigen exposure through the course of pregnancy.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.