Infant RSV Prevention: FDA Grants Approval for Clesrovimab Antibody
Infant RSV: FDA Approval for Clesrovimab Antibody
The FDA has accepted a biologics license application (BLA) for Merck’s clesrovimab (MK-1654), an investigational antibody to protect infants against respiratory syncytial virus (RSV), as per a recent press release. The FDA has also designated June 10, 2025, as the Prescription Drug User Fee Act (PDUFA) date.
Clesrovimab is an extended half-life monoclonal antibody designed for single-dose administration, irrespective of weight. Compared to traditional vaccines that take longer to deliver immunity, monoclonal antibodies provide immediate, albeit shorter-term, protection lasting only a few months, according to the National Institutes of Health.
This application approval stems from results of the Phase 2b/3 CLEVER trial (MK-1654-004) and the ongoing Phase 3 SMART trial, which evaluates the effectiveness of clesrovimab against Merck’s competitor, palivizumab, in children at heightened risk for RSV. Data from the CLEVER trial indicate that clesrovimab reduced RSV-associated hospitalizations by 84.2% compared to placebo, as reported during ID Week 2024 in Los Angeles.
RSV is a highly contagious virus that causes seasonal infections similar to the flu, affecting children and older adults significantly. In the U.S., an estimated 58,000 to 80,000 children under five are hospitalized each year due to RSV infections, with older adults facing 60,000 to 160,000 hospitalizations annually according to the Centers for Disease Control and Prevention.
Worldwide, RSV ranks as the primary cause of hospitalization for otherwise healthy children under one year old, often leading to potentially severe respiratory conditions like bronchiolitis and pneumonia. This results in approximately 3.6 million hospitalizations and 101,000 deaths annually in children under five.
Notably, in October 2024, the FDA approved RSV vaccine Abrysvo targeting lower respiratory tract disease caused by RSV in adults aged 18 to 59. Pregnant women between 32 to 36 weeks of gestation can also receive Abrysvo, thereby protecting their infants from birth to six months of age.
“Despite recent advances in RSV prevention, unmet needs remain for additional effective interventions to help protect infants and continue to help address the burden RSV places on families and the healthcare system,” said Paula Annunziato, M.D., vice president of clinical development at Merck Research Laboratories.
This article was prepared using information from open sources in accordance with the principles of Ethical Policy. The editorial team is not responsible for absolute accuracy, as it relies on data from the sources referenced.