Safety, immunogenicity and effectiveness of inactivated influenza
vaccines in healthy pregnant women and children under 5 years: An
Evidence-Based Clinical Review
Abstract
Background: Pregnant women and young children are at high risk for
influenza complications and, therefore, recommended for annual influenza
vaccination. However, most studies investigating the safety,
immunogenicity and effectiveness of inactivated influenza vaccines (IIV)
were conducted in healthy adults. Therefore, the safety, immunogenicity
and effectiveness of IIV in pregnant women and young children are
underexplored. Objective: In this review, we evaluate the safety
profile, immunogenicity, and effectiveness of IIV in healthy pregnant
women and children <5 years old. Methods: We searched the
electronic databases PubMed, Google Scholar, MEDLINE, Embase, WHO
International Clinical Trials Registry Platform (ICTRP), and UpToDate up
until 8th June 2020. Selection criteria included publications assessing
safety, immunogenicity and effectiveness of IIV in healthy pregnant
women and children <5 years. Results: A total of 60 studies
were selected for the review: 9 on IIV safety, 17 and 11 on
immunogenicity, and 13 and 10 on effectiveness of IIV in pregnant women
and children, respectively. Most randomized controlled trials in
pregnant women included in this review were conducted in low- and
middle-income countries while observation studies were conducted in
high-income countries. Conclusion: IIV were found to be a safe
preventive strategy with moderate immunogenicity and effectiveness
estimates for pregnant women and children <5 years old.
However, the effect sizes depended upon the study design, individual
factors, vaccine type and manufacturing practices, and the antigenic
match between the influenza vaccine strains and the circulating strains.