Reduction in Respiratory Syncytial Virus (RSV)-Related Outpatient and Inpatient Cases Among Infants During the Initial 2024/2025 Season Following Nirsevimab Recommendation in Germany.

After introducing nirsevimab during the 2024/2025 respiratory syncytial virus (RSV) season in Germany, RSV activity in infants under 1 year dropped by 50% in primary care and 50%-70% in secondary care. Inpatients under 6 months showed the greatest reduction. RSV severity decreased with fewer RSV-associated ICU admissions and shorter hospital stays. RSV sequence analysis identified four known polymorphisms in the nirsevimab binding site among inpatients; none associated with resistance. These findings indicate that nirsevimab effectively reduced medically attended RSV disease in infants.