Nirsevimab for RSV

Efficacy of nirsevimab in preventing RSV-associated lower respiratory tract infection in term and late-preterm infants.

Study design: Phase 3 randomized controlled trial.

Population

Number of patients studied: 3012
Inclusion criteria: Infants born at a gestational age of at least 35 weeks
Exclusion criteria: See Section S2 in the study

Interventions

Experimental group: 1998 infants received one dose of nirsevimab (50 mg if <5 kg or 100 mg if ≥5 kg)
Control group: 996 infants received placebo

Primary outcome: Efficacy against hospitalization for RSV-associated lower respiratory tract infection: 76.8% (95% CI, 49.4 to 89.4)

Number Needed to Treat (NNT): 53.1 (95% CI, 29.4 to 250.0) to prevent one hospitalization for lower respiratory tract infection of any cause

Secondary outcomes

Efficacy against very severe medically attended RSV-associated lower respiratory tract infection: 78.6% (95% CI, 48.8 to 91.0)

Safety outcomes or Adverse Events

Adverse events related to nirsevimab or placebo reported in 1.3% of nirsevimab recipients and 1.5% of placebo recipients through 360 days after injection. (See Tables S6 and S7 in the study)

Conclusion

A single dose of nirsevimab provided a consistent level of protection against hospitalization for RSV-associated lower respiratory tract infection and very severe medically attended RSV-associated lower respiratory tract infection during an RSV season.