The U.S. FDA has approved Merck's monoclonal antibody Enflonsia (cesrovimab) to prevent respiratory syncytial virus lower respiratory tract disease in infants, positioning it as a competitor to Sanofi and AstraZeneca’s Beyfortus. The approval comes during a period of upheaval as the CDC's Advisory Committee on Immunization Practices (ACIP) was entirely dismissed, creating regulatory uncertainty. Despite committee vacancies, the ACIP meeting scheduled for late June will proceed, potentially affecting Enflonsia’s recommendation timeline.