The patients, aged 2 to 15, were hospitalized from April 17 to May 1, according to the alert.
Several tested positive for Covid-19 or had positive antibody tests.
Symptoms similar to Kawasaki disease
Kawasaki disease causes inflammation of the walls of the arteries and can restrict blood flow to the heart. It is usually treatable and most children recover without serious problems, but it can be fatal.
At least five of the cases required a ventilator, and more than half of the patients needed blood pressure support. So far, no deaths have been reported among patients in New York City.
Similar cases have also been reported in Italy and Spain.