ArticleLancet regional health. Americas2026
Nirsevimab effectiveness, number needed to immunize and impact on severe RSV outcomes, a test-negative study in Quebec, Canada.
Article in Lancet regional health. Americas, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed, 1 synthesis or guideline pooled it.
- RSV prophylactics for pediatric populations: A product review and meta-analysis of real-world effectiveness.Human vaccines & immunotherapeutics · 2026Pooled it
- Respiratory Syncytial Virus-Related Hospitalizations Among Infants Receiving Nirsevimab.JAMA network open · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
10 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: In 2024-25, Quebec implemented a universally publicly funded infant nirsevimab program. We estimated effectiveness, number-needed-to-immunize (NNI) and impact against severe respiratory syncytial virus (RSV) outcomes. Methods: A test-negative study estimated adjusted effectiveness among nirsevimab-eligible children RSV-tested during emergency room (ER) consultation or hospitalization between October 2024 and March 2025. Eligible children were born during the RSV season (at-birth group) or <6- to <19-month-olds healthy, preterm, with chronic conditions or living in remote regions (catch-up groups). We used 2023-24 respiratory hospitalization rates, RSV-positivity from a systematic hospital-based surveillance network, and Quebec 2024-25 coverage estimates to derive the theoretical NNI and averted hospitalizations. Findings: Effectiveness analyses included 3172 specimens linked to ER consultations (1775 [56·0%] from male and 1397 [44·0%] from female participants; 668 [21·1%] RSV-positive) and 1758 linked to hospitalizations (988 [56·2%] from male and 770 [43·8%] from female participants; 549 [31·2%] RSV-positive). Effectiveness was 86% (95% CI: 82-90) against ER consultation, 89% (95% CI: 84-92) against hospitalization (79% (95% CI: 60-89) for those with chronic diseases and 93% (95% CI: 83-97) for preterm infants), and 88% (95% CI: 58-97) against ICU admission. We estimated 41 at-birth and 58 catch-up immunizations needed to avert one RSV-associated hospitalization. We estimated that 72% (at-birth group) and 59% (catch-up group with 64% coverage by November) of RSV-associated hospitalizations were prevented, potentially increasing to 82% for a hypothetical coverage of 90% by October. Interpretation: Nirsevimab is highly effective and could more substantially impact the RSV burden through broad and timely administration to healthy-term and high-risk infants. Funding: Ministère de la santé et des services sociaux du Québec.
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