Doctors in the UK and Italy have published details of a rare hyperinflammatory disorder in young children which appears to be linked to COVID-19.

Warnings were first issued to UK doctors at the end of April after clinicians in London triggered the alert due to a small cluster of cases with a rare but dangerous reaction they suspected was related to coronavirus infection.

Now the South Thames Retrieval Service who provide paediatric intensive care to 2 million children in South East England have published the “unprecedented cluster of eight children with hyperinflammatory shock” seen in mid April over a 10-day period.

Writing in The Lancet, they said the children were showing features similar to atypical Kawasaki disease which would usually be seen in one to two children per week.

All the children were previously fit and well, they report. Six of the children were of Afro- Caribbean descent, and five of the children were boys. All children except one were well above the 75th centile for weight. Their ages ranged from four to 14 years.

Symptoms were similar in the children who had unrelenting fever (38–40°C) and rash along with conjunctivitis, peripheral oedema, and generalised extremity pain with significant gastrointestinal symptoms, the clinicians from the Evelina London Children’s Hospital Paediatric Intensive Care Unit reported.

All progressed to warm, vasoplegic shock eventually requiring haemodynamic support. And while most of the children had no significant respiratory symptoms, seven of the eight needed mechanical ventilation for cardiovascular stabilisation, the clinicians said.

Every child tested negative for COVID-19 from swab samples yet they clearly had infection or inflammation based on other laboratory findings, the team said. They all later tested positive for SARS-CoV-2 antibody.

One of the children, a 14-year-old boy, died. The others were discharged from paediatric intensive care after less than a week.

“We suggest that this clinical picture represents a new phenomenon affecting previously asymptomatic children with SARS-CoV-2 infection manifesting as a hyperinflammatory syndrome with multiorgan involvement similar to Kawasaki disease shock syndrome,” the team concluded.

“The intention of this Correspondence is to bring this subset of children to the attention of the wider paediatric community and to optimise early recognition and management,” they added pointing out they had now seen more than 20 children with similar symptoms.

Doctors in Italy have also published a detailed report in The Lancet of 10 cases of the rare Kawasaki-like disease which follows similar reports from New York.

Ten cases in the space of a month seen in Bergamo, Italy showed striking similarities to the reports from the London team including positive SARS-CoV-2 antibody tests in eight of them. All of the children survived but showed more serious symptoms than those diagnosed with Kawasaki Disease before the pandemic.

Writing in a linked comment piece, Professor Russell Viner, President of the Royal College of Paediatrics and Child Health said it was crucial to reiterate – for parents and health-care workers alike—that children remain minimally affected by SARS-CoV-2 infection overall.

“Understanding this inflammatory phenomenon in children might provide vital information about immune responses to SARS-CoV-2 and possible correlates of immune protection that might have relevance both for adults and children,” he wrote

He added: “In particular, if this is an antibody-mediated phenomenon, there might be implications for vaccine studies, and might also explain why some children become very ill with COVID-19, while the majority are unaffected or asymptomatic.”