The New Era of Respiratory Syncytial Virus Protection for Infants: A Mini Review of Current Tools for Immunoprophylaxis

AIM: This mini review describes the history of infant respiratory syncytial virus (RSV) immunoprophylaxis and the latest advances in this area. It also reviews the efficacy, safety and impact of the recently introduced prophylactic strategies. METHOD: This narrative review is based on a targeted review of published literature, with emphasis on pivotal clinical trials, regulatory documents and recent real-world evidence. RESULTS: Three immunisation products for preventing RSV in infants have been approved since 2022. These are two long-acting monoclonal antibodies, nirsevimab and clesrovimab, and a maternal RSV vaccine. The efficacy of these interventions has ranged from 49% to 76% against medically attended RSV-associated lower respiratory tract infections and from 55% to 91% against hospitalisation due to RSV-associated lower respiratory tract infection. The efficacy varied between the products and the duration of the follow-up. Similar or higher effectiveness has been reported in post-licensure, real-world evidence studies. Overall, these interventions have been well tolerated, with favourable safety profiles. CONCLUSION: The newly introduced long-acting monoclonal antibodies and the maternal RSV vaccine have proved highly effective and have demonstrated reassuring safety. They have already been implemented in a number of countries and have substantially reduced the RSV burden in infants.