Effectiveness of the live zoster vaccine in patients with type 2 diabetes: a nationwide emulated target trial

Objectives: Real-world studies on its effectiveness in patients with type 2 diabetes mellitus (T2DM) remain limited. This study aimed to evaluate the effectiveness of the live zoster vaccine in patients with T2DM more than 10 years.

Methods: In this target trial emulation study, we utilized a large-scale, nationwide cohort in South Korea, consisting of individuals aged 50 years and older with T2DM from January 1, 2012 to December 31, 2021 (n = 934 945). This cohort was integrated using health insurance data from the Korea Health Insurance Review and Assessment Service, national health screening results from the Korean National Health Insurance Service, and live zoster vaccination data from the Korea Disease Control and Prevention Agency. Vaccine effectiveness in preventing herpes zoster (HZ), postherpetic neuralgia, and hospital admissions for HZ based on International Classification of Diseases 10th edition codes was evaluated in patients with T2DM. In a propensity score-based overlap weighted cohort, Cox proportional hazard models were used to evaluate the adjusted hazard ratios (aHRs) and 95% CIs for the effectiveness of the live zoster vaccine among patients with T2DM.

Results: After propensity score-based overlap weighting, 253 660 patients with T2DM were included (mean age, 62.4 years [standard deviation, 2.3 years]; 138 338 males, 54.5%). Live zoster vaccination was associated with a reduced risk of HZ (aHR 0.59 [95% CI: 0.57–0.61]), postherpetic neuralgia (aHR 0.59 [95% CI: 0.57–0.61]), and hospital admissions for HZ (aHR 0.41 [95% CI: 0.36–0.47]). Vaccine effectiveness was highest within the first-year post-vaccination, with a sustained protective effect lasting up to 6 years. Furthermore, the effectiveness was greater in the non-insulin treatment group compared with the insulin treatment group.

Discussion: Our target trial highlighted that live zoster vaccination significantly reduced the risk of HZ, postherpetic neuralgia, and hospital admissions in patients with T2DM. However, its effectiveness was attenuated in those undergoing insulin treatment.