[{"id":"harm-ep1","name":"RSV-LRTI hospitalization","type":"PRIMARY","unit":"% reduction","p_value":"<0.001","results":[{"ci":"67.8-92.0","arm":"harm-nirs","label":"83.2% reduction; 0.3% (11/4037) vs 1.5% (60/4021)","value":83.2}],"description":"Real-world effectiveness in preventing RSV hospitalizations. This is the endpoint MELODY could not confirm (p=0.07), and HARMONIE delivered with resounding significance."}]

Phase 3b, open-label, randomized (N=8,058; 4,037 nirsevimab, 4,021 standard care). 235 sites in France, Germany, UK. PRIMARY (150 days): RSV hospitalization: nirsevimab 0.3% vs standard care 1.5%. Efficacy: 83.2% (95% CI: 67.8-92.0; p<0.001). Very severe RSV LRTI: 75.7% reduction (95% CI: 32.8-92.9; p=0.004). 180-day follow-up (Lancet 2025): efficacy sustained at 82.7% (95% CI: 67.8-91.5; p<0.0001). Published NEJM December 2023.

N=4,016 nirsevimab, N=4,018 standard care. Grade 1 AEs: 68.7% vs 67.1%. Grade 2 AEs: 36.0% vs 35.7%. AE rates comparable — no safety signal. 1 possibly related SAE: infantile spasms 23 days post-dose (within background rate). Deaths: 0. Safety consistent with MELODY and Phase 2b trials through 365 days.

Published in NEJM Dec 28, 2023. The 83.2% reduction in RSV hospitalizations with a SINGLE DOSE is remarkable. Real-world US data (CDC) showed 77-90% effectiveness across seasons. 180-day extension data in Lancet confirmed durability.

Pragmatic real-world evidence to confirm MELODY efficacy signal. Conducted across France, Germany, UK during 2023-2024 RSV season.