Though Covid was rare and mild in children, some of those infected faced severe multisystem inflammatory syndrome (MIS) and had to be admitted to the intensive care unit (ICU).

An international team led by researchers at the University of Alberta in Canada found that kids older than five years of age and those with high blood markers for inflammation were at the highest risk of developing Covid-related MIS-in children (MIS-C).

According to the US Centers for Disease Control and Prevention (CDC), MIS-C is a condition where different body parts can become inflamed, including the heart, lungs, kidneys, brain, skin, eyes, or gastrointestinal organs.

“Multisystem inflammatory syndrome in children is a new diagnosis, with differing diagnostic criteria that have not been validated,” Dr. Joan Robinson, a paediatrician at the University and co-authors wrote in the paper published in Canadian Medical Association Journal.

“Most of these children lacked a history of contact with a person with proven SARS-CoV-2 infection. Identifying exposure can be difficult as infected contacts may be asymptomatic or may never have been tested,” he added.

In the research, the team included 232 children younger than 18 admitted to 1 of 15 centres – 13 in Canada, 1 in Costa Rica and 1 in Iran – for suspected MIS-C between March 1, 2020, and March 7, 2021.

The patients met the World Health Organization’s definition for MIS-C, which includes fever persisting for at least three days; elevated C-reactive protein, which indicates inflammation; illness involving two or more systems with no obvious microbial cause of inflammation; and positivity for Covid or suspected contact with a positive case.

Most patients (89 per cent) had gastrointestinal symptoms such as pain and dermatological problems like rashes and swelling (85 per cent).

Cardiac involvement was common (59 per cent), as were abnormalities in blood coagulation (90 per cent).

Of the 232 children, 73 (31.5 per cent) were admitted to ICU, and 47 (64 per cent) of them needed treatment for very low blood pressure.

The risk of admission to the ICU was higher in children aged 6-12 years (44 per cent) and 13-17 years (46 per cent) than in children aged 0-5 years (18 per cent).

The authors call for international consensus on MIS-C diagnostic criteria to enhance clinical care and research.