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Nirsevimab Effectiveness at Preventing RSV-Related Hospitalization in Infants
Marie Joelle Jabagi1, Jérémie Cohen2, Marion Bertrand1
1EPI-PHARE Scientific Interest Group in Epidemiology of Health Products, French National Agency for the Safety of Medicines and Health Products (ANSM), French National Fund for Health Insurance (CNAM), Saint-Denis, France.
Insights
Nirsevimab significantly reduced hospitalizations for respiratory syncytial virus lower respiratory tract infections (RSV-LRTIs) in infants. This real-world study confirms nirsevimab
Area of Science:
- Pediatric Infectious Diseases
- Immunology
- Public Health
Background:
- Pivotal trials indicated nirsevimab's efficacy against respiratory syncytial virus-associated lower respiratory tract infections (RSV-LRTIs).
- Real-world effectiveness data for nirsevimab in infant populations is crucial.
Purpose of the Study:
- To assess the real-world effectiveness of nirsevimab in preventing RSV-LRTI hospitalizations among infants.
- To evaluate nirsevimab's impact on RSV-LRTI requiring intensive care or respiratory support.
Main Methods:
- Population-based cohort study utilizing the French National Health Data System.
- Matched 1:1 cohort of nirsevimab-immunized infants and unimmunized controls.
- Propensity score-weighted conditional Cox models to estimate effectiveness for RSV-LRTI hospitalizations and related complications.
Main Results:
- Nirsevimab demonstrated 65% effectiveness in preventing RSV-LRTI hospitalizations (95% CI, 61-69).
- Significant effectiveness was observed for preventing RSV-LRTI requiring PICU (74%) or HDU (64%) admissions.
- Effectiveness was also noted for preventing RSV-LRTI hospitalizations requiring ventilation (66%) or oxygen therapy (67%).
Conclusions:
- A single nirsevimab injection provides substantial real-world protection against RSV-LRTI hospitalization in infants.
- Findings support the use of nirsevimab for broad infant protection against severe RSV disease.
Background:
In pivotal trials, nirsevimab showed promising efficacy in reducing hospitalizations for respiratory syncytial virus-associated lower respiratory tract infections (RSV-LRTIs). Nirsevimab's real-world effectiveness needs to be assessed.
Methods:
This population-based study used the French National Health Data System. All infants born between February 6 and September 15, 2023 were eligible. Each day during the study period (September 15, 2023, to January 31, 2024), all infants newly passively immunized with nirsevimab were matched to unimmunized controls in a 1:1 ratio according to sex, birth month, gestational age, department of residence, and the French Social Deprivation Index (Fdep). Study outcomes included RSV-LRTI-related hospitalization, RSV-LRTI necessitating admission to a pediatric intensive care unit (PICU) or high dependency unit (HDU), and RSV-LRTI requiring ventilation support or oxygen therapy. We estimated nirsevimab effectiveness using propensity score-weighted conditional Cox models.
Results:
The study included 82,474 infants (41,237 in each group) with a median follow-up of 118 days (interquartile range, 76 to 125). The population included predominantly male infants (52.5%) born at term (94.6%), mostly between April and July 2023 (64.0%), and from more advantaged municipalities (FDep first quintile: 29.8%). In total, 342 infants (0.8%) in the nirsevimab group and 992 (2.4%) in the unimmunized group were hospitalized for RSV-LRTI. Nirsevimab's effectiveness was 65% (95% confidence interval [CI], 61 to 69) for RSV-LRTI hospitalizations; 74% (95% CI, 56 to 85) for RSV-LRTI PICU admissions; 64% (95% CI, 55 to 71) for RSV-LRTI HDU admissions; 66% (95% CI, 51 to 76) for RSV-LRTI hospitalization requiring ventilation support; and 67% (95% CI, 57 to 75) for RSV-LRTI hospitalization requiring oxygen therapy. Subgroup and sensitivity analyses yielded consistent effectiveness estimates.
Conclusions:
This study in a nationwide monoclonal antibody infusion setting suggests that a single injection of nirsevimab was associated with substantial protection of infants against hospitalization for RSV-LRTI.
