COVID-19 vaccine effectiveness in people on immunosuppressive therapies: a systematic review and meta-analysis

BACKGROUND: People on immunosuppressive therapies are at increased risk of severe COVID-19, yet vaccine efficacy in these individuals has been inadequately assessed in randomised controlled trials. This systematic review and meta-analysis aims to examine vaccine effectiveness in people with medical conditions commonly treated with conventional synthetic or targeted immunosuppressive therapies. METHODS: with 95% CIs were reported as measures of between-study heterogeneity. This review was registered with PROSPERO (CRD42023434975). FINDINGS: =89·7%) for SARS-CoV-2 infection, 3·72 (1·63-8·47, 85·5%) for hospitalisation, and 3·14 (1·51-6·54, 75·2%) for death. INTERPRETATION: This analysis shows a substantial benefit of vaccination for people on immunosuppressive therapy, particularly after three vaccine doses and against severe outcomes. It also highlights a significantly higher risk of hospitalisation and death in this group than in vaccinated healthy individuals. Assessing booster vaccine effectiveness in these populations against current circulating variants and with updated vaccines remains a priority. FUNDING: National Health and Medical Research Council (Australia).