A five-year-old boy in New York state in the US has died from a rare inflammatory disease believed to be caused by the new coronavirus, Governor Andrew Cuomo said Friday.

"There have been 73 reported cases in NY (state) of children getting severely ill with symptoms similar to Kawasaki disease and toxic shock-like syndrome.

"On Thursday, a 5-year-old boy passed away from these complications, believed to be caused by COVID-19," Cuomo wrote on Twitter.

He added that the state's department of health was investigating and called on parents to seek care immediately if their child had a fever lasting more than five days.

Other symptoms include diarrhea or vomiting, breathing trouble, a paling of skin color, chest pain and lethargy, Cuomo said.

Kawasaki disease is a mysterious illness that primarily affects children up to the age of five and causes the walls of arteries to become inflamed, resulting in fever, skin peeling and joint pain.

A rash and swollen glands can also be a sign and if untreated patients can suffer health failure, but those who are given medical care respond well.

Britain's National Health Service first sounded the alarm last month, warning about a small rise in children infected with the coronavirus that have "overlapping features of toxic shock syndrome and atypical Kawasaki disease."

France, Italy and Spain has also reported several cases.

Treatment for Kawasaki disease involves intravenous immunoglobulin and aspirin and though frightening, most recover without serious issues.

While no link has been formally established to the new coronavirus, scientists believe it could be connected.

In an article published this week in the medical journal The Lancet, British doctors describing eight cases observed in London said it could be "a new phenomenon" affecting previously-asymptomatic children with the coronavirus "manifesting as a hyperinflammatory syndrome".

While youngsters can become infected with the new coronavirus, very few have died or contracted serious symptoms, something that had given solace to parents amid the deadly pandemic.

Cuomo said any confirmed link between COVID-19 and Kawasaki disease would be a worrying development.

"This would be really painful news and would open an entirely different chapter," Cuomo told reporters at his daily briefing Friday.

Earlier this week, Mayor Bill de Blasio said a rising number of cases in New York City was causing concern.

Of the first 15 confirmed cases in the Big Apple, four patients tested positive for COVID-19 and six who tested negative were found to have antibodies, suggesting they had previously been infected.

New York City Health Commissioner Oxiris Barbot said a few cases had also been identified in Boston and Philadelphia.