A rare syndrome in children linked to Covid-19 appears to affect youngsters with African heritage more than those who are white, experts have said.

The Evelina London Children’s Hospital said around 70% to 80% of more than 70 children it had treated for the syndrome were from a black, Asian and minority ethnic (BAME) background.

It comes after a small study of 21 children admitted to the Necker-Enfants Malades hospital in Paris found more than half (57%) had African heritage, compared with 29% who were European and 10% who were Asian.

The main symptoms are a high and persistent fever and a rash, while some children also experience abdominal pain and gastrointestinal problems.

Although some patients have required intensive care, others have responded quickly to treatment and been discharged.

The number of children with the condition is very small but parents must seek urgent medical attention if they are worried about their child’s health

The illness is said to be similar to Kawasaki disease, which mainly affects children under the age of five, with symptoms including a high temperature, rashes, swelling and a toxic shock-style response.

Dr Sara Hanna, medical director at Evelina London Children’s Hospital, said the syndrome was rare.

She added: “More than 70 cases have been treated at Evelina London since mid-April 2020, and a significant proportion of these children have a BAME background, around 70%-80% of cases, including one case where a 14-year-old boy of African Caribbean origin tragically died.

“Research is under way to try to understand the reasons for this distribution of cases and the impact of other factors such as increased BMI (body mass index) and low vitamin D levels, particularly given the diverse population served by the Evelina London in south-east London.

“The number of children with the condition is very small but parents must seek urgent medical attention if they are worried about their child’s health.

“Signs and symptoms of the condition can include prolonged high fever in the absence of an obvious cause like a chest infection, red eyes, abdominal pain, diarrhoea and skin rashes.”

In mid-May, Professor Russell Viner, president of the Royal College of Paediatrics and Child Health, said 75 to 100 children had been affected in the UK so far.

Prof Viner stressed at the time that the condition was very rare, but said it appeared to occur mostly after coronavirus infection.

The study from Paris, published in the British Medical Journal (BMJ), found that all 21 children affected had gastrointestinal symptoms (abdominal pain, often with vomiting and diarrhoea), while other common symptoms were rash (76%) and inflammation of the heart muscle – also known as myocarditis (76%).

The children were aged three to 16 and were admitted to hospital between April 27 and May 11, with 90% having evidence of recent Covid-19 infection.

Despite 17 patients (81%) needing intensive care, all were discharged by May 15 with no serious complications.

The researchers said their findings “should prompt high vigilance” among doctors, particularly in countries with a high proportion of children of African ancestry.

They said more research was needed but factors such as social and living conditions, and genetic susceptibility to the illness, needed to be explored.