Nirsevimab may curb RSV severity
Real-world estimates showed protection across emergency, inpatient, and intensive care settings during Canada’s first universal immunization season.
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By
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Andrea Surnit
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September 18, 2026
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Clinical Scorecard: Nirsevimab may curb RSV severity
At a Glance
| Category | Detail |
|---|
| Condition | Respiratory Syncytial Virus (RSV) |
| Key Mechanisms | Nirsevimab exposure defined as receipt at least 7 days prior to RSV testing. |
| Target Population | Infants younger than 12 months eligible for nirsevimab. |
| Care Setting | Tertiary care pediatric hospitals |
Key Highlights
- Adjusted nirsevimab effectiveness against laboratory-confirmed RSV was 78%.
- Effectiveness was 97% against ICU admission, 79% against inpatient hospitalization, and 77% against ED visits.
- Estimated effectiveness was 90% among infants born prematurely.
- Effectiveness decreased over time: 85% at 7-29 days, 69% at 30-59 days, and 78% at 60-89 days.
Guideline-Based Recommendations
Diagnosis
- RSV testing among symptomatic infants.
Management
- Consider nirsevimab administration for eligible infants.
Monitoring & Follow-up
- Monitor effectiveness over time and across different care settings.
Risks
- Potential misclassification of nirsevimab receipt and variability in testing practices.
Patient & Prescribing Data
Symptomatic infants younger than 12 months.
Nirsevimab may reduce the severity of RSV disease requiring hospital-based care.
Clinical Best Practices
- Encourage universal nirsevimab programs to reduce RSV burden.
- Assess high-risk comorbidities when evaluating treatment options.
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