July 15, 2020

Safety and effectiveness of influenza vaccine during pregnancy

Low rates of influenza vaccination during pregnancy continue despite efficacy in preventing influenza infection in infants. Health care providers may be hesitant to suggest the vaccine to pregnant women due to safety concerns. Though it is generally believed that the benefits of protecting pregnant women and their newborns from influenza complications outweigh the small risks of vaccination, updated evidence is needed to support these recommendations.

This project aimed to determine if influenza vaccination during pregnancy is safe and effective for women and their newborn babies.  We studied women from the 3D Cohort Study (Design, Develop, Discover), comprising 2,366 women recruited during the first trimester of pregnancy (8–14 weeks) in Quebec.

Influenza vaccine during pregnancy was not clearly associated with all-cause hospitalizations in newborns, small birth weight, or being small for gestational age. Our estimates for spontaneous abortions were not conclusive due to relatively low precision. In sensitivity analyses related to the timing of vaccine exposure, we were unable to determine if risk differed according to trimester.

Our study confirms low influenza vaccine uptake in pregnancy, suggesting the need to promote influenza vaccine uptake in this group.

For more information, contact: Autumn Neville, Research Coordinator. autumn.neville@rimuhc.ca

This research was funded by CIHR-DSEN 
Lead investigators: Dr. Anick Berard and Dr. Sasha Bernatsky
Query 19-08 raised by the Public Health Agency of Canada, Infectious Disease Prevention and Control, Centre for Immunization and Respiratory Infectious Diseases