The Evolving Landscape of Respiratory Syncytial Virus (RSV) Prophylaxis in Infants.

Throughout human history, respiratory infections have been among the most common illnesses affecting populations worldwide. Respiratory syncytial virus (RSV) is recognized as one of the major pathogens responsible for a significant disease burden in young children and the elderly population, causing lower respiratory tract infections. Initially identified as the chimpanzee coryza virus in the mid-20th century, it was later named human RSV. This review outlines the discovery of RSV, the initial challenges faced in vaccine development, and the evolution of monoclonal antibodies for infants and vaccines for pregnant mothers to prevent RSV infection in infants. Early vaccine trials enhanced respiratory disease and increased mortality among vaccinated infants. There were subsequent failures with live attenuated vaccines. Research turned toward developing the monoclonal antibody palivizumab, which provided the first practical means of protecting high-risk infants against RSV infection. Subsequent advances in monoclonal antibodies, especially nirsevimab, and the advent of the maternal vaccination program with the Bivalent Prefusion F Vaccination have expanded disease prevention to the population level instead of targeting high-risk infants. These advances promise to reduce hospitalizations and severe disease, improving overall community health. Future priorities include ensuring equitable access, maintaining long-term safety surveillance, and integrating RSV prevention into national immunization programs worldwide.