Title : Early influenza vaccination during pregnancy confers greater protection to infants against influenza infection
Abstract:
Objectives: The primary objective of this systematic review is to identify the optimal timing of immunizing pregnant women to confer the most protection by reducing the incidence of laboratory confirmed influenza or influenza-like-illness in infants less than 6 months of age. Currently, there are gaps in the research regarding the timing of administration during the gestational period to provide maximum immunogenicity to the infant. The research question being addressed is ‘When considering immunizing pregnant mothers with the influenza vaccine, implementing a vaccination program during which trimester in pregnancy would optimize benefits for infants less than 6 months of age in terms of the incidence of laboratory confirmed influenza and influenza-like illness?’
Design: Systematic review / Meta-analysis
Methods: Randomized controlled trials (RCT’s) and observational studies comparing health outcomes of infants and children until 6 months of age born to women who received inactivated influenza vaccine during pregnancy with mothers who did not receive the vaccine or received a control vaccine. The primary outcome was laboratory-confirmed influenza infection of infants. Secondary outcome measures included influenza –like illness diagnosed by a clinician and acute respiratory illness.
Results: 6 studies were included; 2 primary RCT’s and 4 observational studies (prospective and retrospective cohort studies). Forrest plot analysis revealed that vaccinating pregnant mothers in the second and third trimester when compared with any trimester (1,2 and 3) (OR 0.18 vs 0.65) conferred less protection promoting vaccinating in the first trimester
Conclusion: Vaccinating pregnant mothers in the first trimester conferred greatest protection of infants compared to any other trimester.
