BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C), temporally associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been identified in infants <12 months old . Clinical characteristics and follow-up data of MIS-C in infants have not been well described . We sought to describe the clinical course, laboratory findings, therapeutics and outcomes among infants diagnosed with MIS-C.
METHODS: Infants of age <12 months with MIS-C were identified by reports to the CDC's MIS-C national surveillance system . Data were obtained on clinical signs and symptoms, complications, treatment, laboratory and imaging findings, and diagnostic SARS-CoV-2 testing . Jurisdictions that reported 2 or more infants were approached to participate in evaluation of outcomes of MIS-C .
RESULTS: Eighty-five infants with MIS-C were identified and 83 (97.6 %) tested positive for SARS-CoV-2 infection; median age was 7.7 months . Rash (62.4 %), diarrhea (55.3 %) and vomiting (55.3 %) were the most common signs and symptoms reported . Other clinical findings included hypotension (21.2 %), pneumonia (21.2 %) and coronary artery dilatation or aneurysm (13.9 %). Laboratory abnormalities included elevated C-reactive protein, ferritin, d-dimer and fibrinogen . Twenty-three infants had follow-up data; 3 of the 14 patients who received a follow-up echocardiogram had cardiac abnormalities during or after hospitalization . Nine infants had elevated inflammatory markers up to 98 days postdischarge . One infant (1.2 %) died after experiencing multisystem organ failure secondary to MIS-C .
CONCLUSIONS: Infants appear to have a milder course of MIS-C than older children with resolution of their illness after hospital discharge . The full clinical picture of MIS-C across the pediatric age spectrum is evolving.