Although the host factors contributing to the emergence of rheumatological illnesses are still poorly defined, activation of innate immunity and the involvement of IL-1 have been clearly shown as common denominators in the pathogenesis of MIS-C, KD, rheumatic fever, post-EBV, and post-streptococcal reactive arthritis [11,21]. Here, IL1B is linked to COVID-19–associated multisystem inflammatory syndrome in children.