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Case Series of Multisystem Inflammatory Syndrome in Adults Associated with SARS-CoV-2 Infection – United Kingdom and United States, March-August 2020

Our take —

Several CDC case reports and published case series suggest that multisystem inflammatory syndrome due to SARS-CoV-2 infection may not be limited to children. This MMWR describes 27 cases of MIS-A (adults) who had confirmed SARS-CoV-2 infection (either previously or currently) and were hospitalized with severe dysfunction of extrapulmonary organ systems but minimal respiratory illness. However, the clinical presentation, timing, and ascertainment of SARS-CoV-2 infection varied widely, and refinements to the MIS-A case definition will help to estimate the overall burden of disease and guide research on its pathogenesis.

Study design

Case Series

Study population and setting

This report describes 27 patients with multisystem inflammatory syndrome in adults (MIS-A) from three data sources: CDC reports (n=9), published case reports (n=7), and three published case series (n=11). MIS-A was defined as adults (21+ years) who were hospitalized with severe illness, had a positive test result for SARS-CoV-2 during admission or in the prior 12 weeks, had severe dysfunction of at least other extrapulmonary organ system, had laboratory evidence of severe inflammation, and did not have severe respiratory illness. The cases were voluntarily reported to CDC by clinicians and health departments using a case report form developed for MIS-C (multisystem inflammatory syndrome in children). A literature search on August 20, 2020 identified the additional published case reports and case series.

Summary of Main Findings

Among the 16 patients (56% women, age range: 21-50 years, 56% with underlying conditions) included in case reports (9 from CDC reports and 7 from published case reports), all had evidence of cardiac involvement, 13 had GI symptoms at admission, and 10 had evidence of pulmonary involvement despite minimal respiratory symptoms. Inflammatory markers (CRP and ferritin) and markers of coagulopathy (D-dimer) were elevated in all. Timing of SARS-CoV-2 testing was variable; only 10 showed evidence of SARS-CoV-2 by RT-PCR at initial assessment for MIS-A, 4 had positive antibody tests at admission, and 2 were positive 14 and 37 days prior to admission but were negative at the time of admission. Ten required intensive care, and two patients died. Data from the published case series (n=11 from 3 case series) were similar: age range 20-50, at least four with negative PCR tests at admission but high IgG antibody titers, elevated inflammatory markers, and heterogeneous presentation (two patients had large vessel strokes, others with cardiac dysfunction, GI symptoms, and dermatologic symptoms, but mild respiratory symptoms).

Study Strengths

The report includes a thorough review of MIS-A cases in the United States and the United Kingdom.


Given that this was a case series of voluntarily reported cases to CDC and published case series/reports, the results likely do not capture all MIS-A cases in the US or the UK during this time frame, and also cannot be used to estimate the overall burden of MIS-A in the US or UK population. The case definition included required participants have evidence of SARS-CoV-2 with a current or previous positive result on either PCR, antigen, or antibody tests. It’s possible that some patients with MIS-A related symptoms never received testing for SARS-CoV-2, which could have resulted in exclusion of some cases. The timing of SARS-CoV-2 infection and MIS-A is still unclear and cannot be adequately inferred from this data.

Value added

There have been several well-described reports of MIS-C, but this is one of the most comprehensive reports of MIS-A in the United States and the United Kingdom.

This review was posted on: 23 October 2020