Maternal Immunization Against Respiratory Syncytial Virus: An Integrative Review of Efficacy, Safety, and Implementation

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infection in young infants and accounts for substantial morbidity, hospitalization, and mortality worldwide, with the highest burden concentrated in the first months of life, when immunological and anatomical immaturity favors severe disease. Maternal vaccination has emerged as a strategy to bridge this window of vulnerability through the transplacental transfer of neutralizing antibodies. This integrative review synthesizes scientific articles published between 2022 and 2026, including systematic reviews, meta-analyses, narrative reviews, and position statements from national and international scientific societies, addressing the epidemiology, clinical manifestations, diagnosis, mechanism of action, efficacy, safety, and public health impact of maternal RSV immunization. The bivalent prefusion F protein vaccine (RSVpreF; Abrysvo®), administered as a single intramuscular dose between 32 and 36 weeks of gestation, induces maternal IgG that is transferred to the fetus and confers passive protection during the first six months of life. In the phase 3 MATISSE trial, vaccination demonstrated 81.8% efficacy against severe RSV lower respiratory tract infection within 90 days of birth and 69.4% within 180 days, alongside reductions in hospitalization. The safety profile was favorable, with predominantly mild and transient adverse events; a numerical imbalance in preterm birth remains under surveillance and underlies the precautionary gestational window. Maternal vaccination and long-acting monoclonal antibodies (nirsevimab) are best regarded as complementary rather than competing strategies. Current evidence supports maternal immunization as one of the most effective measures to reduce the burden of RSV disease in early infancy.