A significant reduction in hospitalizations and intensive care admissions among infants with respiratory syncytial virus (RSV) is being observed following the widespread implementation of nirsevimab, a long-acting monoclonal antibody. Recent data from multiple countries, including the Netherlands and the United States, demonstrate the substantial impact of this preventative measure.
Dramatic Drop in Hospitalizations
Studies indicate a marked decrease in severe RSV cases following the introduction of nirsevimab. In the Netherlands, data presented by RIVM (the National Institute for Public Health and the Environment) show a substantial decline in the number of infants requiring intensive care due to RSV infection. Similar trends are emerging in the US, with one study suggesting an approximately 86% reduction in RSV-related lower respiratory tract infection (LRTI) hospitalizations in the 2023-2024 season compared to pre-nirsevimab levels (2016-2023, excluding the COVID-19 pandemic years of 2020-2021 and 2021-2022). The protective effect appears to extend into the following season, with a 55% reduction observed in hospitalizations during the 2024-2025 season.
Nirsevimab and ICU Admissions
While nirsevimab has been established as effective against hospitalization for RSV, recent research is focusing on its impact on the most severe cases – those requiring admission to the intensive care unit (ICU). Data from 24 states, analyzed by the Centers for Disease Control and Prevention (CDC) between December 2024 and April 2025, are providing valuable insights into this area. The CDC currently recommends nirsevimab to prevent severe RSV-related disease in infants.
Who is at Risk and Who Should Receive Nirsevimab?
RSV is a leading cause of hospitalization among infants in the United States, with as many as 80,000 children under five years old admitted to hospitals annually. Premature infants are at particularly high risk. The American Academy of Pediatrics (AAP) recommends RSV immunization with nirsevimab or clesrovimab for infants under 8 months of age born during or entering their first RSV season, particularly if their pregnant parent was not vaccinated against RSV during pregnancy.
A Shift in Vaccination Recommendations
The positive findings regarding nirsevimab come at a time when US regulators have recently deemphasized the importance of childhood vaccinations. Earlier this month, the CDC reduced the number of diseases it recommends routine vaccination against from 17 to 11. Vaccines previously included in the standard childhood schedule, including the RSV vaccine, are now recommended only for “high-risk groups.” This shift in policy underscores the importance of targeted preventative measures like nirsevimab for protecting vulnerable infants.
How Nirsevimab Works
Nirsevimab is a long-acting monoclonal antibody designed to provide infants with passive immunity against RSV. Unlike traditional vaccines, which stimulate the body’s own immune system to produce antibodies, nirsevimab directly provides the antibody, offering immediate protection. What we have is particularly beneficial for young infants whose immune systems are still developing.
Looking Ahead
The data collected during the 2023-2024 and 2024-2025 RSV seasons are providing crucial real-world evidence of nirsevimab’s effectiveness. Ongoing surveillance and research will continue to refine our understanding of its long-term impact and optimal implementation strategies. The observed reductions in hospitalizations and ICU admissions represent a significant step forward in protecting infants from the serious consequences of RSV infection.
The findings from the Instituto de Investigacion Sanitaria de Santiago de Compostela in Spain, which followed over 12,000 infants eligible for nirsevimab, showed that over 94% of eligible infants received the antibody, allowing researchers to assess its population-level impact. This high uptake rate is a key factor in the observed success of the program.
