Multisystem inflammatory syndrome in children (MIS-C) has been affecting children during the coronavirus pandemic.
Symptoms include a rash, fever and abdominal pain.
The disease shares some features with Kawasaki disease, as well as toxic shock syndrome.
MIS-C is connected to the same virus, SARS-CoV-2, that causes Covid-19, researchers at King’s College London have found.
However, adults are more likely to develop Covid-19 while children are more likely to develop MIS-C.
Scientist have so far been unable to work out why MIS-C almost exclusively affects children while Covid-19 is much less of a risk to youngsters.
More than two-thirds of children in the latest Kings College MISC-C study tested positive for SARS-CoV-2 antibodies, proving they had been infected in the past.
Treatment for the disease involves steroids, anticoagulants, immunoglobulin and, in the most severe cases, ventilation.
Deaths from MIS-C are very rare, however a 14-year-old boy in London died from the disease. and there have been four reported deaths in the US.