Three children have now died in less than one week of a "inflammatory Kawasaki-like condition linked to coronavirus."
The syndrome, described by authorities as "truly disturbing", mirrors the Kawasaki disease, which causes prolonged fever, abdominal pain, diarrhoea and other symptoms.
Andrew Cuomo, New York Governor, said two children who had coronavirus have died of the condition. Three children have now succumbed to it in total in New York City alone after a five-year-old boy became gravely ill.
Speaking today at a press conference in Manhattan, New York City, Gov Cuomo said: “This is the last thing that we need at this time, with all that is going on, with all the anxiety we have, now for parents to have to worry about whether or not their youngster was infected.
“One of the few rays of good news was young people weren’t affected. We’re not so sure that is the fact anymore.”
More than 70 children are said to have been infected by the illness across New York alone.
Now, Gov Cuomo said authorities are making tackling it the "priority".
It is understood the disease, similar to toxic-shock syndrome, also causes an inflammation of blood vessels in children under five, including babies and toddlers.
In some cases, it can lead to heart disease and further complications.
Scientists are still trying to determine whether the syndrome is linked with the new coronavirus because not all children with it have tested positive for the virus.
Cuomo said New York's health department, which on Wednesday issued an advisory to healthcare providers about the so-called pediatric multi-system inflammatory syndrome, were reviewing 73 cases with children showing similar symptoms across the state.
"While rare, we are seeing some cases where children affected with the COVID virus can become ill with symptoms similar to the Kawasaki disease or toxic shock-like syndrome that literally causes inflammation in their blood vessels," the governor said.
New York City Mayor Bill de Blasio tweeted on Tuesday: "If your child is experiencing a persistent fever, rash, abdominal pain or vomiting, call your doctor right away."
He also said that NYC Healthy has instructed all healthcare providers to report any patients under the age of 21 with the symptoms.
Kawasaki disease is a rare childhood condition, which typically causes a high temperature that lasts for five days or more.
It is always treated in hospital.
