Risks of Alopecia Areata in Long COVID: Binational Population-Based Cohort Studies from South Korea and Japan

The study investigates the long-term risk of alopecia areata (AA) following SARS-CoV-2 infection using large, binational cohort studies from South Korea and Japan. The research analyzed data from a Korean nationwide cohort (10,027,506 individuals) and a Japanese claims-based cohort (12,218,680 individuals). Results showed that SARS-CoV-2 infection is associated with a 66% increased risk of developing AA, with this risk persisting for up to 6 months. Severe COVID-19 cases further increased the risk, while receiving two or more doses of the COVID-19 vaccine before infection reduced the risk. The findings highlight an elevated risk for AA as a component of long COVID.