The herpes zoster (HZ) vaccine is recommended for adults in the US ages ≥60 years who do not have weakened immune systems. It is unclear how the risk of HZ varies according to age and disease conditions in younger patients with autoimmune or inflammatory (AI) diseases. This study was undertaken to evaluate the age-stratified incidence of HZ in patients with AI diseases as compared to older adults for whom the HZ vaccine is currently recommended by the US Centers for Disease Control and Prevention.