An outbreak of Kawasaki disease was noted in 2020 in Italy during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The authors’ objectives in which to evaluate the incidence and features of patients with Kawasaki-like disease diagnosed during the SARS-CoV-2 epidemic. They looked at cases of hemodynamic instability during the acute phase of the disease (Kawasaki disease shock syndrome [KDSS]) and those that might fulfill the criteria of macrophage activation syndrome (MAS).

All patients diagnosed with Kawasaki or Kawasaki-like disease who presented over the past 5 years (January 1, 2015, and April 20, 2020) before the COVID pandemic at this institution (Bergamo, Italy) were reviewed and compared with those who were diagnosed after the onset of the pandemic (February 18 to April 20, 2020).

Patients with Kawasaki-like presentations were defined according to the 2017 criteria of the American Heart Association, including both classic type and incomplete types. KDSS was defined as Kawasaki disease accompanied by systolic arterial hypotension, a decrease from baseline systolic blood pressure of at least 20%, or the appearance of peripheral hypoperfusion. MAS was defined by using the Pediatric Rheumatology International Trials Organization criteria used in systemic juvenile idiopathic arthritis and commonly used for other systemic autoinflammatory diseases (Kawasaki disease and pediatric systemic lupus erythematosus). Data reviewed from medical records included demographic data, presenting symptoms and treatments, contact with confirmed or suspected cases of coronavirus disease 2019, vital signs, laboratory data (white blood cell count, lymphocyte count, erythrocyte sedimentation rate, C-reactive protein, procalcitonin, ferritin, fibrinogen, pro B-type natriuretic peptide, troponin I, natural killer activity, and interleukin 6 concentrations), electrocardiogram, and echocardiogram data. Current or previous infection with SARS-CoV-2 was obtained by reverse-transcriptase quantitative polymerase chain reaction in nasopharyngeal and oropharyngeal swabs and by serological testing for SARS-CoV-2 immunoglobulin M and immunoglobulin G. Patients were treated with 2 g/kg of intravenous immunoglobulin and aspirin dosed on the basis of Kobayashi score with 2-week methylprednisolone taper.

Group 1 (pre–coronavirus disease) comprised 19 patients (7 boys and 12 girls; mean age: 3 years old) and group 2 (during coronavirus disease) included 10 patients (7 boys and 3 girls; mean age: 7.5 years old). A total 8 of 10 patients in group 2 were positive for SARS-CoV-2 immunoglobulin G or immunoglobulin M or both. A total of 5 presented with classic Kawasaki, and 5 presented with incomplete form. Comparing the 2 groups (group 1 versus group 2), there was a significant difference in disease incidence (0.3 patients per month versus 10 patients per month), mean age (3.0 vs 7.5 years), cardiac involvement (2 of 19 vs 6 of 10), KDSS (0 of 19 vs 5 of 10), MAS (0 of 19 vs 5 of 10), and need for adjunctive steroid treatment (3 of 19 vs 8 of 10; all P < .01).

A 30-fold increased incidence of Kawasaki-like disease was seen at this institution. Children diagnosed with Kawasaki disease after the SARS-CoV-2 epidemic onset showed evidence of an immune response to the virus, were older, had a higher rate of cardiac involvement, had respiratory and gastrointestinal symptoms, were more resistant to intravenous immunoglobulin treatment, had more severe disease, and had features of MAS.

Within the past year, multisystem inflammatory syndrome in children has been diagnosed around the world. Some of these children will fulfill criteria for complete and incomplete Kawasaki. Affected children tend to be older, and there is disproportionate number of Hispanic and African American children. They present with fever, gastrointestinal symptoms, rash, conjunctivitis, mucous membrane involvement, neurocognitive symptoms, lymphadenopathy, and respiratory symptoms. Clinicians should be aware of this syndrome to ensure proper care of patients.