Nirsevimab (Beyfortus) may reduce severe respiratory syncytial virus infections among infants
1. In this large case-control study across 7 tertiary pediatric hospitals, receiving Nirsevimab (Beyfortus) among symptomatic infants with respiratory syncytial virus (RSV) significantly reduced the burden of severe disease and ICU visits.
Evidence Rating Level: 1 (Excellent)
Respiratory syncytial virus (RSV) is a major cause of emergency department visits and hospitalization in infants, and nirsevimab is a long-acting monoclonal antibody designed to prevent severe RSV disease during an infant’s first RSV season. This study evaluated the real-world effectiveness of nirsevimab against RSV-related emergency department (ED) visits, hospitalizations, and intensive care unit (ICU) admissions during the 2024–2025 RSV season in Ontario and Quebec. The investigators conducted a test-negative case-control study across 7 tertiary pediatric hospitals participating in the SPRINT-KIDS surveillance network. They included symptomatic infants younger than 12 months who underwent RSV testing between October 27, 2024, and March 1, 2025, with nirsevimab receipt at least 7 days before testing. Of 1,942 eligible infants, 683 (35.2%) were RSV-positive cases and 1,259 (64.8%) were RSV-negative controls, while 429 infants (22.1%) had received nirsevimab. Receiving nirsevimab was substantially less common among RSV-positive infants than RSV-negative infants (7.0% vs 30.3%; P < .001). After adjustment, estimated effectiveness against laboratory-confirmed RSV disease was 78% (95% CI, 68%-84%), with effectiveness of 77% (95% CI, 62%-86%) against ED visits, 79% (95% CI, 66%-87%) against hospitalization, and 97% (95% CI, 85%-100%) against ICU admission. Effectiveness remained high among premature infants (90%; 95% CI, 66%-98%) and infants with comorbidities (86%; 95% CI, 37%-98%). Overall, the findings suggest that nirsevimab was highly effective at preventing severe RSV disease requiring hospital-based care during the first season of universal publicly funded administration in Ontario and Quebec.
Click here to read this study in JAMA Network Open
Image: PD
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