Over a dozen children have suffered a type of toxic shock syndrome (TSS) believed to be linked to COVID-19, The Guardian reported.
All of the children have been treated in the ICU and at least one of the children has had to be placed on life support. It is not known if any children have died, The Guardian noted.
Italy has seen a similar trend, Reuters noted, with "extraordinarily large" numbers of children under nine years of age presenting with what looks like severe Kawasaki disease.
One hospital in the northern town of Bergamo reported over 20 cases of severe pediatric heart inflammation wihtin the past months - six times more than it usually sees in an entire year, pediatric heart specialist Matteo Ciuffreda said.
He added that pediatric specialists in both Madrid and Lisbon had confirmed similar findings.
The Health Service Journal quoted a letter to general physicians in northern London, in which NHS officials, noted that pediatric patients presented with a "multi-system inflammatory state requiring intensive care" and that the cases "have in common overlapping feature of toxic shock syndrome and atypical Kawasaki disease with blood parameters consistent with severe COVID-19 in children." Some of these children required treatment for heart inflammation.
It notes that there may be a COVID-19-related inflammatory syndrome in children, or an "as yet unidentified, infectious pathogen associated with these cases."
In addition the UK's Paediatric Intensive Care Society sent a similar warning to specialists working in paediatrici ICUs in the country's hospitals, The Guardian said.
Some of the children had confirmed cases of coronavirus, while others' tests had come back negative. However, serological evidence of possible previous COVID-19 infections was also observed.
Symptoms of the new syndrome, which doctors suspect may be a "post-infection inflammatory response," include abdominal pain, gastrointestinal symptoms, and cardiac inflammation. Some of the children presented with persistent fever and rashes as well. When tested, blood tests showed severe inflammation similar to that of adult COVID-19 patients.
Most of the affected children have Kawasaki disease, but Professor Chris Whitty, the UK government's chief medical officer, says that it is "entirely plausible" that the disorder was caused by the virus, "at least in some cases."