Health Secretary Matt Hancock told reporters at Downing Street that he was “very worried” by the development, which is now being investigated by one of the United Kingdom’s most senior experts.
Children have so far escaped the worst health effects of the coronavirus pandemic however little is still known about the disease, how it spreads and what it does to the body.
Children affected by the new condition have “overlapping features of toxic shock syndrome and atypical Kawasaki disease”. Kawasaki disease is a rare illness that largely affects children under five and involves the swelling of blood vessels in the body. It can trigger a temperature, rash or swollen glands in the neck.
Abdominal pain, gastrointestinal symptoms and cardiac inflammation have been common features among seriously ill children over recent weeks. Some have had to be treated in intensive care units.
The illness has been discovered in children who tested positive to the virus, as well as those who have not. There is also some evidence of “possible preceding” COVID-19 infection in some children.
Chief medical officer Chris Whitty said: “This is a very rare situation but I think it is entirely plausible that this is caused by this virus – at least in some cases – because we know that in adults, who of course have much more disease than children do, there are big problems with the inflammatory process and this looks rather like an inflammatory process.
“Therefore given we’ve got a new presentation of this at the time of a new disease, the possibility … that there is a link is certainly plausible. But numbers are very small and the key thing is that if parents are worried, phone up and get advice.”
NHS England national medical director Stephen Powis has asked NHS England’s national clinical director for children and young people to investigate “as a matter of urgency” whether there was a link with the coronavirus outbreak.
The UK death toll rose to 21,092 on Monday, however the actual figure is much higher because thousands of deaths in care homes and private houses have not been added to the tally. The outbreak has killed 83 NHS staff and 16 care home workers.
Schools remain shut and the government appears unlikely to open them once it starts easing the nationwide lockdown.
“It remains the case that the great majority of children either don’t get coronavirus or if they do, the symptoms are minor,” Whitty said. “That doesn’t mean sadly that is absolutely true: there are still a small number of cases, including some very severe cases. But they are much less than adults.”
Whitty said the reason schools had been closed and would remain closed was not because the virus presented a major danger to children, but because the closures contributed to lowering the overall transmission of the virus.
“There is quite a debate at the moment around the world in science about what contribution do children make to the actual spread of this virus between families, around the country,” he said.
“Is it different for example, between young children and older children, which it may be. But unfortunately we do not yet have direct data that really helps us, remembering this is a new disease.
“While I think it remains the case we think the contribution of children at school to the spread of this virus is probably less than for example the flu, we do think it certainly contributes.”
Of the 18,749 people who have died from coronavirus in England’s hospitals, nine were aged between zero and 19. Some 137 were between 20 and 39 years old, and 1505 between 40 to 59 years old.
The president of the Royal College of Paediatrics and Child Health, Russell Viner, stressed only a small number of children have become severely ill.
“New diseases may present in ways that surprise us, and clinicians need to be made aware of any emerging evidence of particular symptoms or of underlying conditions which could make a patient more vulnerable to the virus,” he said.
Bevan Shields is the Europe correspondent for The Sydney Morning Herald and The Age.