University of Calgary doctor's study sheds light on mystery of long COVID in kids

New international research led by a University of Calgary doctor is offering new insights into the prevalence of long COVID in children who are sick enough that their caregivers take them to hospital.

The study, published Friday in the journal JAMA Network Open, followed 1,884 kids who tested positive for COVID-19 in 36 emergency rooms. The period was between March 2020 and January 2021.

According to Dr. Stephen Freedman, a professor of pediatrics and emergency medicine in the University of Calgary's Cumming School of Medicine, researchers followed up with the families from eight countries 90 days after their hospital visit. They wanted to find out if the children were experiencing any new, returning or persistent symptoms.

"We found that approximately six per cent of children had a complaint that met the definition of long COVID," he said.

"This was significantly higher in certain groups … most notably those who were hospitalized, where it actually reached 10 per cent of all children."

Children with more symptoms initially and kids over the age of 14 were also more likely to report the post-COVID condition, according to Freedman, who is the study's senior author.

Fatigue and weakness were the most common symptoms reported three months later. Children who were hospitalized tended to report more gastrointestinal symptoms later on.

What's unique about this study, Freedman said, is researchers used a control group for comparison.

Even after adjusting for a number of variables, they found children who tested positive were more likely to report health problems 90 days later than a control group made up of kids who tested negative in the ER.

Just under three per cent of the control group children had health problems later on. Five per cent of those who were hospitalized and COVID-negative had symptoms three months later.

"Almost all children are getting infected with COVID at some point in time or already have been infected, [so] the magnitude of even a small increase in long COVID symptoms across the population can be a significant burden for children," Freedman said.

"[This study] talks about the importance of minimizing the number of children who are getting infected with COVID and the importance of reducing spread when possible."

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The findings come at a time when Alberta is experiencing an uptick in COVID-19 transmission driven by the more transmissible BA.5 subvariant.

"Reported rates of long COVID in adults are substantially higher than what we found in children," said Dr. Nathan Kuppermann, co-principal investigator at the University of California.

"Our findings can inform public health policy decisions regarding COVID-19 mitigation strategies for children and screening approaches for long COVID among those with severe infections."

What the study doesn't show is how disabling post COVID symptoms are for kids. According to Freedman, researchers plan to delve into that next.

"We really don't know the burden of these symptoms," he said.

"There's a big difference if something is mild and parents simply report it versus something that impedes a child's going to school, their ability to do their activities of daily living, to socialize with other children and their family. So that is a real missing piece of the puzzle that we're hoping to address through future research."