Clesrovimab for Prevention of RSV Disease in Healthy Infants.

Summary

In a randomized, placebo-controlled trial of 3614 infants, a single 105‑mg intramuscular dose of clesrovimab reduced RSV‑associated medically attended lower respiratory infection by 60.4% and hospitalizations by 84.2% through 150 days, with serious adverse events similar to placebo.

Key Findings

• Single 105 mg intramuscular dose reduced RSV medically attended lower respiratory infection by 60.4% (95% CI 44.1–71.9; P<0.001).
• RSV-associated hospitalizations were reduced by 84.2% (95% CI 66.6–92.6; P<0.001).
• Serious adverse events occurred at similar rates to placebo (11.5% vs 12.4%).

Clinical Implications

Clesrovimab may serve as an effective seasonal immunoprophylaxis option to reduce RSV-related clinical burden in infants, potentially complementing or offering an alternative to existing strategies like nirsevimab.

Limitations

• Head-to-head comparisons with existing long-acting antibodies (e.g., nirsevimab) were not performed.
• Efficacy and safety beyond 150 days and across multiple seasons remain to be established.

Future Directions

Head-to-head trials versus current standard prophylaxis, durability across seasons, cost-effectiveness analyses, and evaluation in special populations (preterm subgroups, comorbidities).