Risks of cutaneous immune‐related adverse events in long COVID: Multinational cohort studies in South Korea, Japan, and the UK.

Previous research has not investigated the persistent cutaneous immune‐related adverse events (cirAEs) related to long COVID to investigate the long‐term sequelae. This multinational study, using a propensity‐matched overlap weighting method, utilizes large national claims‐based cohorts, using ICD‐10 code diagnosis, focusing on patients aged ≥20 years from three countries: South Korean, Japanese, and the British cohorts. To estimate the risk of cirAEs in long COVID, the persistence or emergence of cirAEs occurring 4 weeks after the initial SARS‐CoV‐2 infection, we employed a Cox proportional hazard regression model. The Korean cohort (n = 5,937,373; mean age 49.2 years [SD: 13.2]), the Japanese cohort (n = 4,307,587; 42.5 years [13.6]), and the UK cohort (n = 395,435; 71.0 years [8.07]) were presented. An increased risk of cirAEs in long COVID was observed (HR, 1.10; 95% CI, 1.06–1.14) in Korean cohort, while a similar association was observed in Japanese and UK cohorts. The long‐term risk of cirAEs in long COVID was higher in more severe COVID‐19 cases (1.31; 1.22–1.39). Unlike the increased risk of cirAEs in long COVID, COVID‐19 vaccination attenuated the risk, especially with two or more doses (1.03; 0.95–1.11) or heterologous regimens (0.98; 0.76–1.27). The time attenuation effect indicated a sustained risk for up to 6 months postinfection (<3 months: 1.13 [1.07–1.19]; 3‐6 months: 1.14 [1.06‐1.22]). SARS‐CoV‐2 infection is associated with an increased risk of cirAEs in the aspect of long COVID. Vaccination might reduce this risk, highlighting the need for preventive strategies in long COVID management. [ABSTRACT FROM AUTHOR]