Experts have suggested a new inflammatory syndrome in children is a result of Covid-19, as other researchers say antibody tests can help diagnose the rare disease.

Researchers led by the Imperial College Academic Health Science Centre (AHSC) have identified links to Covid-19 in a new and distinct condition in children.

The illness, named Paediatric Inflammatory Multisystem Syndrome Temporally associated with SARS-CoV-2 (PIMS-TS), was first recognised in April and has had less than 200 identified cases in England.

In the study published on Monday, out of 58 children suffering from severe inflammatory symptoms admitted to eight hospitals in England, 45 had evidence of current or past Covid-19 infection.

The majority of children with signs of infection also had antibodies for the virus, the study found, which suggests PIMS-TS occurs after Covid-19 – potentially due to an overreaction of the immune system.

The test will be used to understand how many people have suffered from Covid-19 in our communities but we have found another use identifying PIMS-TS in these sick children

Although there is no certain link between the illness and Covid-19, researchers said the discovery of a new inflammatory condition during the outbreak is unlikely to be a coincidence.

The syndrome has been compared 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.

However, PIMS-TS is thought to include abdominal pains and diarrhoea more often, alongside the joint symptoms of persistent fever.

Blood tests also show different results, as children with PIMS-TS show more inflammation and cardiac enzymes, indicating strain on the heart.

The new syndrome also appears to affect proportionately more black and Asian people.

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

In the study published in the Journal of the American Medical Association, researchers found PIMS-TS seems to affect older children more, with an average age of nine-years-old.

Kawasaki disease is mostly seen in younger children, with an average patient age of four.

Dr Julia Kenny, a consultant in paediatric infectious diseases and immunology at Evelina London, said: “Our analysis has shown that this is indeed a new condition.

“Untreated, there is a risk of severe complications in very unwell children, but with early identification and treatment the outcome is excellent, with the children we are reviewing after discharge completely well.”

Researchers at the University of Birmingham also found that antibody testing can be used to help diagnose the new syndrome.

In a study of eight hospitalised children between the ages of seven and 14 with PIMS-TS symptoms, the researchers found all of them tested negative for Covid-19 when given a PCR test.

However, when given an antibody test, every child had high levels of antibodies for the virus, with patterns indicating the infection likely occurred weeks or months before.

The researchers said their work raises the possibility that children who may not have been unwell previously could be at risk of developing the new syndrome.

Dr Alex Richter, lead researcher and consultant immunologist at the University of Birmingham’s Institute of Immunology and Immunotherapy said: “We have designed a sensitive antibody test that can be used to detect exposure to SARS-CoV-2 infections.

“The test will be used to understand how many people have suffered from Covid-19 in our communities but we have found another use identifying PIMS-TS in these sick children.”