Global health experts are investigating reports of a rare but serious illness affecting children and its links to coronavirus after UK medics raised the alarm.
The World Health Organisation (WHO) has asked a network of clinicians around the world to be on "alert" for the condition after NHS England aired concerns to staff.
Fewer than 20 children in England have been admitted to hospital with the syndrome, which causes a toxic shock-style inflammatory reaction.
The illness may be caused by the novel coronavirus but experts are not sure because some of the affected children have not tested positive for Covid-19.
The syndrome was first flagged after NHS England wrote to medics and asked them to remain on high alert for signs of the condition.
It is said to be similar to Kawasaki disease, which mainly affects children under the age of five, with symptoms including a high temperature for five days or more, rashes and swollen glands in the neck.
WHO technical lead for Covid-19, Dr Maria Van Kerkhove, said: “We are aware of this report, which came out of the United Kingdom, about a small number of cases amongst children with this inflammatory response.
“We’re looking at this with our clinical network.
“There are some recent rare descriptions of children in some European countries that have had this inflammatory syndrome, which is similar to the Kawasaki syndrome.
“What we’ve asked for is for the global network of clinicians to be on alert for this, and to ensure that they capture information on children systematically so that we could better understand what is occurring in children, and so that we could better improve our understanding and guide treatment.
“But it seems to be very rare and only in maybe one or two countries so far and additional countries that have not recorded this yet, but this is something that the clinical network is looking into specifically.”
WHO officials stressed that the vast majority of children who get Covid-19 will have a mild infection and “recover completely”.
Executive director of the WHO health emergencies programme, Dr Mike Ryan, told a press briefing in Geneva: “The Sars-Cov-2 virus causing Covid-19 obviously is causing inflammation and attacks tissue, other than lung tissue.
“We are in a situation where clinicians are looking at what those other effects of having this coronavirus infection are.
“And we’ve seen this in the past with many emerging diseases, they don’t necessarily only attack one type of tissue, there can be multiple organs affected and many of you have seen the reports of other organs that have been affected with this disease.
“So it’s really important that this information is shared around the world."
He explained that it is important for paediatricians and clinicians to get time to collect information about the condition. But reassured parents that while they should be keeping an eye on ill children it is a "rare complication".
Meanwhile, the global health body said in its tri-weekly briefing that Covid-19 can “wreak havoc” and “cause upheavals”.
Going forward, people may need to “adjust the way we lead our lives” while the virus is present, WHO experts added.
The WHO’s director-general Dr Tedros Adhanom Ghebreyesus said: “This virus can wreak havoc. It’s more than any terrorist attack. It can bring political, economic and social upheavals.
“More than ever, the human race should stand together to defeat this virus.”