Effectiveness of maternal vaccination with quadrivalent inactivated influenza vaccine in pregnant women and their infants in 2019-2020

ABSTRACT

Objectives

Influenza is associated with an increased risk for serious illness, hospitalization, and death in pregnant women and young infants. Our aim was to estimate the effectiveness of a quadrivalent inactivated influenza vaccine (QIV) in pregnant women and their infants during 2019–2020.

Methods

A QIV vaccine was offered to pregnant women followed in a maternity hospital. Women were contacted weekly during the influenza season and asked about symptoms. Polymerase chain reaction testing in pharyngeal samples was offered to pregnant women and infants with influenza-like illness. A Bayesian beta-binomial model was used.

Results

We studied 636 pregnant women (406 vaccinated and 230 unvaccinated) and 474 infants (281 of mothers vaccinated in pregnancy and 193 of unvaccinated mothers). Using a Bayesian beta-binomial model, it was estimated that influenza vaccination of pregnant women reduced their logit to develop laboratory-confirmed influenza by −4.2 (95% CI −3,7 − 4,7) and the logit of their infants to develop laboratory-confirmed influenza by −4.2 (95% CI −3.6, −4.9). The QIV effectiveness against laboratory-confirmed influenza was 43.5% in pregnant women and 31.4% in infants.

Conclusion

Maternal influenza vaccination with QIV in pregnancy reduced the odds of pregnant women and their infants to develop influenza.

Clinical trial registration

www.clinicaltrials.gov identifier is NCT04723771.

KEYWORDS:

• Effectiveness
• infants
• influenza vaccination
• pregnant woman
• quadrivalent influenza vaccine

Acknowledgments

We are grateful to all pregnant women who have participated in the study, as well as to the healthcare personnel for their assistance. All authors agree to take responsibility and be accountable for the contents of the article and to share responsibility to resolve any questions raised about the accuracy and integrity of the published work.

Declaration of interests

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Author contributions

Conceptualization and methodology: H.C.M. and A.R.; formal analysis: V.R. and M.A.T.; investigation: H.C.M., S.S., G.A., V.P., G.D., M.S., P.K., M.T., P.A., E.K., E.S., laboratory diagnosis: A.K. and A.M.; writing – original draft preparation: H.C.M.; review for intellectual content and editing: S.S., G.A., V.P., V.R., M.A.T., A.P., G.D., M.S., P.K., M.T., P.A., E.K., E.S., A.K., M.T., A.M., P.D., D.L., and A.R.; supervision: H.C.M., D.L., and A.R. All authors agree to take responsibility and be accountable for the contents of the article and to share responsibility to resolve any questions raised about the accuracy r integrity of the published work.

Additional information

Funding

This work was funded by Sanofi Pasteur (grant number: GQM00022). Sanofi Pasteur had no involvement in the design of the study, the statistical analysis or the interpretation of the results; however they were provided the opportunity to review the manuscript.