Epidemiological insights into chronic urticaria, vitiligo, alopecia areata, and herpes zoster following <scp>COVID</scp>‐19 infection: A nationwide population‐based study

The long-term complications of coronavirus disease 2019 (COVID-19) continue to cause global concern. This study aimed to estimate the incidence and risk of chronic urticaria, vitiligo, alopecia areata, and herpes zoster following COVID-19 infection. Only participants confirmed by real-time reverse transcription-polymerase chain reaction tests to have COVID-19 were enrolled in the COVID-19 group. The matched cohort without COVID-19 was enrolled randomly at a ratio of 1:1. The incidence and risk of chronic urticaria, vitiligo, alopecia areata, and herpes zoster were assessed in both groups using univariable and multivariable Cox proportional hazard analyses. A total of 4 976 589 COVID-19 patients (9.58% of the total population of South Korea) and an equivalent number of matched non-infected control subjects were analyzed. Chronic urticaria, vitiligo, alopecia areata, and herpes zoster manifested at higher rates within the COVID-19 cohort, even after multivariable adjustment for potential confounders. COVID-19 may increase the risk of developing chronic urticaria, vitiligo, alopecia areata, and herpes zoster.