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

Abstract

Background 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. Methods A living systematic review and meta-analysis, with 5monthly 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. Results A total of 50 publications, covering approximately 7.6million 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. Conclusions 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.