RSVpreF vaccination in pregnancy: a meta-analysis of maternal-fetal safety and infant efficacy

In May 2023, the United States Food and Drug Administration approved a Pfizer©-sponsored (Pfizer, New York, NY, USA) bivalent respiratory syncytial virus prefusion F protein-based vaccine (RSVpreF) RSV vaccine (AbrysvoTM [Pfizer]) for use during pregnancy to prevent neonatal/infant RSV infection. In February of 2022, trials sponsored by GSK© (Brentford, England, UK) on a similar RSVpreF vaccine were halted because of the identification of a safety signal related to preterm births. As these vaccines use identical pre-fusion F-protein technology, we sought to synthesize the existing data on their effectiveness and safety. We identified all randomized controlled trials and used RevMan 5.4.1 (The Cochrane Collaboration, England, UK) to perform the analysis with 95% confidence intervals and risk ratios (RRs). We found many maternal side effects were more prevalent in the RSVpreF group, with more local reactions, blood disorders, fatigue, joint pain, cardiac disorders, headache, fever, gastrointestinal disorders and pregnancy complications. The vaccinated group demonstrated significant reductions in RSV-lower respiratory tract cases (RR, 0.44 [0.33, 0.57]; P<0.00001), severe respiratory illness (RR, 0.29 [0.19, 0.44]; P<0.00001), and hospitalizations (RR, 0.40 [0.24, 0.67]; P=0.0005). RSVpreF vaccination was associated with a higher incidence of preterm delivery (RR, 1.24 [1.08, 1.44]; P=0.003). No significant difference in neonatal deaths was observed (RR, 1.42 [0.70, 2.89]; P=0.34). In conclusion, RSVpreF vaccination results in systemic adverse events and an increase in preterm delivery. Vaccination appears to have acceptable short-term newborn safety, but is not related to a significant decrease in neonatal death.