Real-world effectiveness and safety of nirsevimab, RSV maternal vaccine and RSV vaccines for older adults: a living systematic review and meta-analysis.

Abstract

The long-acting monoclonal antibody nirsevimab and respiratory syncytial virus (RSV) vaccines became available for prevention of severe RSV-associated disease in 2023. While clinical trials showed good efficacy and safety, their restrictive inclusion criteria, small sample sizes and short follow-up limit generalisability. We aimed to summarise real-world evidence on the effectiveness and safety of nirsevimab, RSV maternal vaccine and RSV vaccines for older adults. A living systematic review and meta-analysis, with 5 monthly updated searches in three databases was performed. Eligible studies were published from 1 December 2022 to 10 March 2025. Meta-analyses for the effectiveness of nirsevimab and RSV vaccines were carried out using random-effects model. Safety data were summarised narratively. A total of 50 publications, covering approximately 7.6 million people, were included. Nirsevimab showed 80.7% effectiveness (95% CI: 75.7% to 85.7%; seven studies) against RSV-related emergency department visits, 80.7% (95% CI: 76.1% to 85.2%; 17 studies) against hospital admissions and 75.6% (95% CI: 63.3% to 87.9%; eight studies) against intensive care unit admissions. The effectiveness of RSV vaccines for older adults against RSV-related hospital admissions was 79.6% (95% CI: 73.8% to 85.3; three studies). No effectiveness data were available for RSV maternal vaccine. No severe adverse events were reported for nirsevimab, while RSV vaccines in older adults had fewer than 10 Guillain-Barré syndrome cases per million doses. No severe adverse events were reported for RSV maternal vaccine, although evidence was limited. Our review demonstrated high effectiveness of nirsevimab in reducing RSV-related healthcare utilisation in infants and a favourable safety profile. More evidence is needed for evaluating RSV vaccines in pregnant people and older adults. CRD42025643585.