Sixty-four children and teens in New York State are suspected of having a mysterious inflammatory syndrome that is believed to be linked to COVID-19, the New York Department of Health said in an alert issued Wednesday. A growing number of similar cases — including at least one death — have been reported in other parts of the U.S. and Europe, though the phenomenon is still not well-understood.

Pediatricians say parents should not panic; the condition remains extremely rare. But researchers also are taking a close look at this emerging syndrome, and say parents should be on the lookout for symptoms in their kids that might warrant a quick call to the doctor — a persistent high fever over several days and significant abdominal pains with repeated vomiting, after which the child does not feel better.