askST: What is multi-system inflammatory syndrome in kids and how is it linked to Covid-19?

MIS-C typically develops about two to six weeks after a child has been infected with Covid-19.
MIS-C typically develops about two to six weeks after a child has been infected with Covid-19.ST PHOTO: KUA CHEE SIONG

SINGAPORE - Four children here infected with Covid-19 have also come down with a rare and severe inflammatory syndrome, the Ministry of Health (MOH) announced last Saturday (Nov 6).

Among those with multi-system inflammatory syndrome in children (MIS-C) is a four-year-old boy who is in the children's intensive care unit, with his breathing supported by mechanical ventilation.

The four children are among 8,000 paediatric Covid-19 cases in Singapore since the start of the pandemic, MOH added. An international review from 26 countries in May last year reported that 14 in 10,000 children with Covid-19 infection contracted MIS-C.

What is this syndrome that affects a small minority of children afflicted with Covid-19? The Straits Times answers your questions.

Q: What are the key symptoms?

Symptoms of MIS-C include persistent fever above 38.5 deg C for three days or more, with difficulty breathing, headache, neck swelling, rash, swollen hands and feet or abdominal pain, according to MOH.

These symptoms are similar to those for Kawasaki disease, which has been linked to various viral or bacterial infections and occurs in 150 to 200 children a year in Singapore.

An article in The Lancet medical journal in September last year said that although the features of Kawasaki disease and MIS-C are similar, the Covid-19-related syndrome appears to be more acute, resulting in sicker children.

Q: Who does it typically affect among children?

Obesity is the main risk factor for MIS-C identified thus far, Dr Liew Woei Kang, who specialises in paediatric immunology, told ST.

Certain races, such as black people in the United States, are over-represented in MIS-C numbers as well.

The Lancet article said a surge in cases of MIS-C had not been reported in Asia at the time.

This is despite the annual incidence rates of Kawasaki disease in Asian countries, especially Japan and Korea, being 10 to 20 times higher than those in Europe and America.

MIS-C also appears to affect older children, compared with Kawasaki disease.

The three other children who contracted MIS-C in Singapore so far are a two-month-old girl and two boys, aged three and eight.

Q: How soon after getting Covid-19 does MIS-C develop?

MIS-C typically develops about two to six weeks after a child has been infected with Covid-19, according to another study published in The Lancet in May this year.

Some children develop MIS-C after discharge from hospital for the initial infection.

In other cases, children who never needed to be admitted for the initial infection had to be admitted instead for MIS-C.

The two-month-old girl with MIS-C in Singapore was previously admitted to hospital for Covid-19 on Oct 12 and discharged on Oct 19. She was admitted to hospital again on Nov 3 for the inflammatory syndrome.

Q: What is the recovery rate for MIS-C?

A study of 33 children with MIS-C from three New York City hospitals found low mortality, with one patient dying. There was also almost universal recovery.

Out of the four children with MIS-C here, two have recovered and have been discharged.

To treat MIS-C, doctors may administer steroids, aspirin and intravenous gamma globulin to control the "exuberant" immune response and its effects on the child, said infectious diseases expert Leong Hoe Nam.

Dr Liew, a consultant paediatrician at the Paediatric Allergy Immunology Rheumatology Centre, said: "The treatment of MIS-C is largely supportive, targeting the organs that have been affected.

"As a large percentage of MIS-C patients have low blood pressure, many require intensive care unit admission and cardiac medications."