Kuang-Jen ChienCheng-Chung James WeiShih-Hui HuangChun-Yu ChenHo-Chang KuoYao-Min HungPei-Lun LiaoJing-Yang HuangMing-Fang ChengKen-Pen Weng2026-02-042026-02-042024-07-1610.1097/JCMA.0000000000001137https://scholars.csmu.edu.tw/handle/123456789/5051<jats:sec> <jats:title>Background:</jats:title> <jats:p>The associations of coronavirus disease (COVID-19) with Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) remain unclear. Few large-scale studies have estimated the cumulative incidence of MIS-C and KD after COVID-19 in children.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods:</jats:title> <jats:p>Data were obtained from TriNetX. After propensity score matching was completed, data from 258 645 patients with COVID-19 (COVID-19 group) and 258 645 patients without COVID-19 (non-COVID-19 group) were analyzed using Cox regression. Hazard ratio (HR), 95% CI, and cumulative incidence of MIS-C and KD were calculated for both groups. A stratified analysis was performed to validate the results.</jats:p> </jats:sec> <jats:sec> <jats:title>Results:</jats:title> <jats:p>After matching for age at baseline and sex, the risks of MIS-C and KD were higher in the COVID-19 group than in the non-COVID-19 group (HR: 3.023 [95% CI, 2.323-3.933] and 1.736 [95% CI, 1.273-2.369], respectively). After matching for age at baseline, sex, race, ethnicity, and comorbidities, the risks of MIS-C and KD remained significantly higher in the COVID-19 group than in the non-COVID-19 group (HR: 2.899 [95% CI, 2.173-3.868] and 1.435 [95% CI, 1.030-2.000]). When stratified by age, the risk of MIS-C was higher in the COVID-19 group—for patients aged &gt;5 years and ≤5 years (HR: 2.399 [95% CI, 1.683-3.418] and 2.673 [95% CI, 1.737-4.112], respectively)—than in the non-COVID-19 group. However, the risk of KD was elevated only in patients aged ≤5 years (HR: 1.808; 95% CI, 1.203-2.716). When stratified by COVID-19 vaccination status, the risks of MIS-C and KD were elevated in unvaccinated patients with COVID-19 (HR: 2.406 and 1.835, respectively).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion:</jats:title> <jats:p>Patients with COVID-19 who are aged &lt;18 and ≤5 years have increased risks of MIS-C and KD, respectively. Further studies are required to confirm the role of COVID-19 in the pathogenesis of MIS-C and KD.</jats:p> </jats:sec>[SDGs]SDG3journal-article