An investigation by medical experts has launched into a possible link between coronavirus and an inflammatory disease found among infants.

It follows a rise in children being admitted to hospital with the symptoms of Kawasaki disease, which include “multi-system inflammation” and flu-like symptoms.

Some of the children have tested positive for coronavirus.

Here’s what you need to know.

Why are doctors worried about Kawasaki disease?

Doctors in northern Italy, which was one of the hardest-hit areas of Covid-19, have reported large numbers of children with what appears to be Kawasaki disease.

A hospital in the northern town of Bergamo has seen more than 20 cases of severe vascular inflammation in the past month.

This is six times as many as it would expect to see in a year, according to paediatric heart specialist Matteo Ciuffreda.

Doctors have also made similar observations in the UK. An urgent alert sent out to GPs from NHS England said that intensive care departments in both London and other parts of the UK have been treating severely sick children with unusual symptoms.

This included "multi-system inflammation", with flu-like symptoms, and some, but not all, of these children tested positive for coronavirus.

NHS England said that it knew of fewer than 20 such cases in the country where an association has been noted by clinicians. According to BBC News, an NHS England spokesperson has said investigations will continue, but no link has yet been established.

In a coronavirus news briefing on Monday (April 27), Health Secretary Matt Hancock explained that he was “very worried” and that medical authorities were currently looking closely at the issue.

England’s national medical director, Stephen Powis, told the British briefing that he had also become aware of reports of severely ill children with symptoms similar to the Kasawaki disease in the past few days.

However, Mr Powis stressed that it was too early to determine a link with the coronavirus, explaining, “I’ve asked the national clinical director for children and young people to look into this as a matter of urgency.”

He added: “We’re not sure at the moment.”

However, in the United States, a leading paediatric society says that it has yet to see something similar to this.

What is Kawasaki disease?

The NHS says: “Kawasaki disease is a condition that mainly affects children under the age of 5. It's also known as mucocutaneous lymph node syndrome.”

Characteristic symptoms are a high temperature that lasts for five days or more, with:

  • a rash
  • swollen glands in the neck
  • dry, cracked lips
  • red fingers or toes
  • red eyes

After a few weeks, and with the correct treatment, the symptoms become less severe, but it can take longer than this in some children, explains the NHS.

What causes Kawasaki disease?

The NHS explains that the cause of Kawasaki disease isn't fully understood, but a child may be more likely to develop it if they inherit certain genes from their parents.

Great Ormond Street Hospital for Children adds, “Doctors do not yet know exactly what causes Kawasaki disease. It is probably due to a combination of factors.

“Some children may be genetically predisposed to the condition, and environmental factors such as infections, and the way a child’s body responds to that infection, could play a part too.”

Who is usually affected by Kawasaki disease?

Around eight in every 100,000 children develop Kawasaki disease in the UK each year.

Research carried out in England from 1998 to 2003 found that 72 per cent of children with Kawasaki disease were under the age of 5.

The condition was also shown to be 1.5 times more common in boys than girls, explains the NHS.

When should I contact my GP?

The NHS notes: “See your GP urgently, or call 111 if you can't speak to a GP, if your child is unwell and has the above symptoms.

“If your baby is less than six months old, it's even more important to see your GP or call 111 straight away.”

However, the symptoms of Kawasaki disease can be similar to those of other conditions that cause a fever in children.

The Royal College of Paediatrics and Child Health (RCPCH) also advises parents to seek urgent help (call 999 or go to A&E) if their child is:

  • Becoming pale, mottled and feeling abnormally cold to the touch
  • Has pauses in their breathing (apnoeas), has an irregular breathing pattern or starts grunting
  • Has severe difficulty in breathing becoming agitated or unresponsive
  • Is going blue round the lips
  • Has a fit/seizure
  • Becomes extremely distressed (crying inconsolably despite distraction), confused, very lethargic (difficult to wake) or unresponsive
  • Develops a rash that does not disappear with pressure (the 'Glass test')
  • Has testicular pain, especially in teenage boys

How is Kawasaki disease treated?

Kawasaki disease is always treated in the hospital, and it's best if treatment begins as soon as possible, the NHS explains.

“The sooner treatment starts, the quicker the recovery time and there's less risk of complications developing,” adds the NHS.

Intravenous immunoglobulin (IVIG), a solution of antibodies, and aspirin are the two main medicines used to treat Kawasaki disease.

How dangerous is Kawasaki disease?

The NHS explains that Kawasaki disease causes the blood vessels to become inflamed and swollen.

This can lead to complications in the blood vessels that supply blood to the heart (coronary arteries).

About 25 per cent of children with Kawasaki disease experience complications with their heart.

If the condition does go untreated, complications can be fatal in about two to three per cent of cases.

Due to this, the condition has become the leading cause of acquired heart disease - heart disease that develops after birth - in the UK.

Should I be worried?

As of yet no link has been established between coronavirus and Kawasaki disease.

Experts have stressed that very few children become severely ill with coronavirus, and evidence from around the world suggests that they are the population least affected by the disease.

Following exposure to coronavirus, children seem to be more resilient to serious lung infection, and the numbers admitted to intensive care units are relatively low, experts explain.