Anti-inflammatory treatments have been used, with good responses being recorded for intravenous immunoglobulin (IVIG), with or without corticosteroids. Oxygen is often needed. Supportive care is key for treating clinical complications. Most children who receive expert hospital care survive.Knowledge of this newly described syndrome is evolving rapidly. Its clinical features may appear somewhat similar to Kawasaki disease, a rare disease of unknown origin that typically affects young children, in which blood vessels become inflamed throughout the body. It can also show features of other serious inflammatory conditions of childhood, including toxic shock and macrophage activation syndromes. Nevertheless, it appears to be a separate syndrome. Older children tend to be affected.This emerging condition has been defined slightly differently (using different names), by the World Health Organization (WHO), the Royal College of Paediatrics and Child Health (RCPCH), and the Centers for Disease Control and Prevention (CDC). Although the condition is thought to follow SARS-CoV-2 viral infection, antigen or antibody tests are not always positive. Exclusion of alternative causes, including bacterial and other infections, is essential for differential diagnosis. Some general clinical guidance has been provided by the RCPCH, the National Institutes of Health, the American College of Rheumatology, and the American Academy of Pediatrics.Clusters of new cases have been reported two to six weeks after local peaks in viral transmission. The disease is thought to be driven by a delayed biological mechanism in certain predisposed children.
History
Cases of Kawasaki disease with concurrent SARS-CoV-2 infection have been recorded among children in Europe and in the United States since 7 April 2020, when a report was published by the American Academy of Pediatrics regarding a case of classic Kawasaki disease in a six-month old girl who tested positive for COVID-19 in California. In this case, COVID-19 did not appear to have significant clinical implications.On 25 April, concerns were initially raised in the United Kingdom regarding a cluster of children of various ages presenting with a multisystem inflammatory state who required intensive care, and who all displayed "overlapping features of toxic shock syndrome and atypical Kawasaki disease with blood parameters consistent with severe COVID-19 in children." Details of the eight cases which helped trigger this alert (not all with confirmed exposure to COVID-19) were later reported in The Lancet, where the authors summarized the clinical picture as "a hyperinflammatory syndrome with multiorgan involvement similar to Kawasaki disease shock syndrome." Accounts of analogous cases – including some that appeared less clinically severe – were also being informally shared among clinicians around Europe. The EUs Early Warning and Response System flagged suspected cases in Austria, Germany and Portugal that had tested positive for SARS-CoV-2. In Bergamo, at the heart of the COVID-19 epidemic in Lombardy, a cluster of 20 cases of Kawasaki disease appeared to be roughly equivalent to the number commonly recorded there over the course of three years.