At least 285 US children have developed a serious inflammatory condition linked to the coronavirus and while most recovered, the potential for long-term or permanent damage is unknown, two new studies suggest.
The papers, published online Monday in the New England Journal of Medicine, provide the fullest report yet on the condition.
The condition is known as multisystem inflammatory syndrome in children. It is considered uncommon and deaths are rare; six children died among the 285 in the new studies.
Including cases in Europe, where it was first reported, about 1,000 children worldwide have been affected, a journal editorial said.
The federal Centers for Disease Control and Prevention's case definition includes current or recent COVID-19 infection or exposure to the virus; a fever of at least 100.4 for at least 24 hours; severe illness requiring hospitalisation; inflammatory markers in blood tests, and evidence of problems affecting at least two organs that could include the heart, kidneys, lungs, skin or other nervous system.
Digestive symptoms including nausea and diarrhea are common. Some children may have symptoms resembling Kawasaki disease, a rare condition in children that can cause swelling and heart problems.