Misclassification of cases of Kawasaki disease and of other inflammatory and infectious diseases of childhood whose case definitions overlap with MIS-C could skew understanding of the new entity, such as the frequency of coronary artery aneurysms. Another concern is that clinically less severe cases of the new entity may be missed, and that the actual spectrum of disease severity could be broader, especially given the reliance on early observations of severe disease for provisional case definition. Some statistical modeling has been used to explore possible subdivision of cases satisfying the CDCs case definition into three distinct subgroups based on underlying clinical similarities: Class 1, characterized by pronounced multiorgan involvement, with little overlap with Kawasaki disease or acute COVID-19; Class 2, more predominantly characterized by respiratory symptoms typical of acute COVID-19; Class 3, a clinically less severe grouping, where rashes and mucosal symptoms are prevalent, with less multiorgan involvement, and generally greater overlap with Kawasaki disease. A suggestion that research into the biology of the disease might benefit from considering cases of Kawasaki disease and of the provisionally defined entity in conjunction is debated. In adults
There has been uncertainty as to whether the condition is confined to children, and the appropriateness of excluding adults from case definitions has been questioned. Sporadic reports exist of a similar life-threatening condition, denominated  multisystem inflammatory syndrome in adults (MIS-A), which also usually requires intensive care.
In a minority of cases, cytokine blockers have been used as a supplemental therapy to inhibit production of IL-6 (tocilizumab) or IL-1 (anakinra); TNF-α-inhibitors (infliximab) have also been used. Inotropic or vasoactive agents are often used for children with cardiac dysfunction and hypotension. Anticoagulants have been used. Low-dose aspirin has been used as an antiplatelet drug.Treatment strategies are being considered to prevent serious long-term complications such as coronary artery aneurysms (the main complication of Kawasaki disease). Close outpatient follow-up by a paediatric cardiology team has been recommended. Causes
While it has been hypothesized that the condition is related to COVID-19, it has also been emphasized that the potential link  "is neither established nor well understood." A temporal association between SARS-CoV-2 infection and clinical presentation of the syndrome is plausible. A causality assessment found that temporality was among the five (out of nine) Bradford Hill criteria that supported a causal relationship between SARS-CoV-2 infection and the development of the syndrome. Further characterization of the syndrome is essential to identify risk factors and help understand causality. It is unclear to what extent this emerging syndrome has a similar aetiology to Kawasaki disease (a condition predating the emergence of SARS-CoV-2, which is currently thought to be triggered by a distinct viral agent). Although some cases resemble toxic shock syndrome, there is no evidence that staphylococcal or streptococcal toxins are involved. The role of comorbidities is unclear. Improved understanding will have potential implications for clinical management. Genome-wide association studies are expected to provide insights on susceptibility and potential biological mechanisms.