Scores of UK and US children have been affected by a rare inflammatory disease linked to coronavirus.
A number of children have also been diagnosed with the disease – which can cause symptoms similar to toxic shock syndrome – elsewhere in Europe.
Up to 100 UK children have been affected. Some have needed intensive care while others recovered quickly.
In April, NHS doctors were told to look out for a rare but dangerous reaction in children.
This was prompted by eight children becoming ill in London, including a 14-year-old who died.
Doctors said all eight children had similar symptoms when they were admitted to Evelina London Children’s Hospital, including a high fever, rash, red eyes, swelling and general pain.
Most of the children had no major lung or breathing problems, although seven were put on a ventilator to help improve heart and circulation issues.
Doctors are describing it as a “new phenomenon” similar to Kawasaki disease shock syndrome – a rare condition that mainly affects children under the age of five. Symptoms include a rash, swollen glands in the neck and dry and cracked lips.
But this new syndrome is also affecting older children up to the age of 16, with a minority experiencing serious complications.
Dr Liz Whittaker, clinical lecturer in paediatric infectious diseases and immunology, at Imperial College London, said the fact that the syndrome was occurring in the middle of a pandemic, suggests the two are linked.
“You’ve got the Covid-19 peak, and then three or four weeks later we’re seeing a peak in this new phenomenon which makes us think that it’s a post-infectious phenomenon,” she said.
This means it is likely to be something related to the build up of antibodies after infection.
Prof Russell Viner, president of the Royal College of Paediatrics and Child Health, said the majority of children who have had the condition have responded to treatment and are getting better and starting to go home.
The syndrome is “exceptionally rare”, he said.
“This shouldn’t stop parents letting their children exit lockdown,” Prof Viner added.
He said understanding more about the inflammatory disease “might explain why some children become very ill with Covid-19, while the majority are unaffected or asymptomatic”.
Children are thought to make up just 1-2% of all cases of coronavirus infection, accounting for less than 500 admissions to hospital.