Efficacy and effectiveness of Herpes zoster vaccination in adults with diabetes mellitus: a systematic review and meta-analysis of clinical trials and observational studies

AimThe risk for Herpes zoster (HZ) and its complications is higher in people with diabetes mellitus (DM). Our aim is to assess efficacy and effectiveness of the currently available live-attenuated zoster vaccine (LZV) and recombinant zoster vaccine (RZV) in adults with DM.MethodsA Systematic Review and Meta-analysis of clinical trials and observational studies comparing incidence of HZ and its complications in vaccinated and unvaccinated people with DM was performed, on PubMed, Cochrane, Clinical Trials.gov and Embase databases, up to January 15th, 2023. Risk of bias was assessed through the Cochrane Collaboration tool and the Newcastle-Ottawa Scale. The protocol was registered on the PROSPERO website (CRD42022370705).ResultsOnly three observational studies reported LZV efficacy and effectiveness in people with DM. A lower risk for HZ infection (MH-OH Ratio 95% CI = 0.52 [0.49, 0.56] was observed, for unadjusted analysis, and 0.51 [0.46, 0.56] for adjusted analysis, both with P < 0.00001 and no heterogeneity). No data on LZV safety were reported. A pooled analysis of two trials comparing RZV and placebo, showed a reduced risk for HZ incidence: (95% CI Odds Ratio: 0.09 [0.04-0.19]), with no difference in severe adverse events and mortality.ConclusionsIn our meta-analysis of three observational studies LZV showed a 48% effectiveness in reducing HZ incidence in adults with diabetes whereas in a pooled analysis of two RCTs, RZV showed a 91% efficacy. No data are available on the effects of vaccination on the incidence and severity of HZ-related complications among subjects with diabetes.