Background Herpes zoster causes substantial morbidity in older and immunocompromised adults. The recombinant zoster vaccine is preferentially recommended, but policy decisions increasingly require real-world evidence on effectiveness across diverse populations, dosing patterns, and potential waning of protection over time. Methods We conducted a systematic review and meta-analysis of observational studies (cohort and case-control) assessing recombinant zoster vaccine effectiveness among adults (≥18 years). Analytical observational studies published in any language between Jan 1, 2017, and Oct 31, 2025, were eligible. Methodological quality was assessed using the Joanna Briggs Institute standardised critical appraisal instruments. This study is registered on PROSPERO (CRD420251266323). Findings A vaccine effectiveness of 80·0% (95% Confidence Intervals CI: 74·1–84·5) was found for immunocompetent adults and 64·3% (95 CI: 61·4–67·0) for immunocompromised adults. Vaccine effectiveness after four years was 73·0% (68·0–76·0). For people with autoimmune diseases, vaccine effectiveness was 66·2%, 95% CI 62·7–69·5). Similar vaccine effectiveness was found for adults with diabetes (66·6%, 41·8–80·9), liver disease (62·7%, 50·4–72·0), and older adults (75·1% among ≥80 years). Pooled vaccine effectiveness for postherpetic neuralgia for the immunocompetent population was 84·7% (95% CI 60·9–94·0) and for immunocompromised populations was 38·7% (95% CI 19·1–53·5). Subgroup and complication estimates were based on fewer studies and, where evidence was sparse or outcome definitions varied across datasets, should be interpreted as exploratory. Substantial heterogeneity (I 2 ≥ 75%) was observed in 59% of the meta-analyses. Conclusion For all at-risk groups, the recombinant zoster vaccine provides sustained clinically meaningful real-world benefit in preventing herpes zoster. Evidence for protection against complications and in some subgroups is supportive but limited, particularly where estimates are based on few studies or variable outcome definitions.
Mbinta et al. (Wed,) studied this question.