Children in the United States are showing symptoms of coronavirus and some already tested positive.
In New York, more than a dozen children have been hospitalised with mysterious syndrome associated with the disease.
Mayor Bill de Blasio made the announcement on Tuesday in an urgent alert for parents and doctors.
De Blasio disclosed that four of the children tested positive for COVID-19, while six had antibodies, suggesting they had been infected with the virus.
He tweeted: “We’ve detected 15 cases of multi-system inflammatory syndrome detected in children in NYC hospitals. 4 patients tested positive for COVID-19 while 6 others had antibodies.
“We haven’t seen any fatalities yet, but we are very concerned by what we’re seeing. We’re learning more every day about how COVID-19 affects the body. This is a ferocious disease”.
De Blasio urged parents to seek immediate medical help if their child is experiencing a persistent fever, rash, abdominal pain or vomiting.
New York’s Health Department said an inflammatory syndrome, recently reported by the United Kingdom, is being observed among children and young adults in their city and others in the U.S.
The department, in a bulletin, added that the illness is “potentially associated with COVID-19.”
It disclosed that the patients, aged 2 to 15, showed symptoms associated with toxic shock or Kawasaki disease and that over half of the hospitalised children “required blood pressure support and five required mechanical ventilation”.
New York has been the epicentre of coronavirus in the U.S.
Currently, of the 72,000 deaths in America, 25,000 were in New York.
In Germany, a top disease control official, Lothar Wieler, said there may be the second and third waves of coronavirus infections.