Dr Hilary has revealed the six main symptoms of Kawasaki disease parents need to look out for in their children.
The medical expert appeared on today's episode of Good Morning Britain to discuss the worrying illness that researchers say is linked to Covid-19.
Hilary was quizzed by hosts Piers Morgan and Susanna Reid over the rare syndrome and told viewers what the key symptoms to keep an eye out for in sick children are.
"Kawasaki disease has always been around - it's a rare condition affecting about 8 in 100,000 children." Dr Hilary said.
He added: "The cause is unknown but it causes an inflammation of blood vessels.
"What we're seeing now is a similar sort of syndrome. It's thought to be a delayed immune reaction to Covid-19.
"The children who have this won't necessarily test positive for Covid-19 - some do. But some won't."
He went on to say: "Those who don't often have Covid-19 antibodies. So they weren't acutely infected with Covid-19 but subsequently, a number of weeks later, that's why we're seeing this now after the peak here in the UK.
"We're seeing a number of children with symptoms similar to Kawasaki disease and that is why we are seeing a number of children displaying a delayed immune reaction to Covid-19.
"Those symptoms are swollen glands, a fever, a rash, sometimes tummy pain, peeling skin, and low blood pressure."
Last month, Health Secretary Matt Hancock announced the new symdrome is being investigated by experts "with great urgency".
He stressed that the illness is rare, however many teachers and partents have shared their anxiety for the Government's plans to have children return back to school June 1.
