MONTREAL -- Serious cases of COVID-19 were very rare among Canadian children during the first wave of the pandemic, a new study by Canadian researchers shows.

However, they warn this should not be seen as a reason not to vaccinate young children.

The study, published Monday in the Canadian Medical Association Journal, looked at 264 children hospitalized in Canada between March 25 and Dec. 31, 2020, found to have SARS-CoV-2.

Forty-three percent of these children had been hospitalized for another reason, such as a bone fracture, and it was only at the time of their admission that the coronavirus was detected.

"If you look at the numbers in total, that's only 150 children hospitalized for COVID-19 in the first two waves here in Canada," said the study's co-lead author Dr. Fatima Kakkar with the CHU Sainte-Justine Hospital. "So these are very small numbers when you compare them with what happened in adults."

Researchers originally thought children might be at greater risk of severe disease, since that's typically what happens with a respiratory infection in a pediatric population.

Among the 150 children admitted directly with coronavirus, the most common symptoms were fever and cough.

Half were severely ill; 21 per cent were admitted to intensive care and 13 per cent required respiratory or cardiac support.

More than three per cent of Canadian children, a high among all age groups in the country, have antibodies to COVID-19, indicating exposure to the virus.

"The relatively small number of pediatric admissions shows that children have less severe infections than adults, even though they are potentially infected more often," said Dr. Kakkar.

"We often talk about children having comorbidities and being sicker ... but 60 per cent had no comorbidities," she said. "These were healthy children who were hospitalized for the disease. However, when you look at the severity, the most severe cases were in children who had comorbidities, like obesity, major neurodevelopmental disorders."

Deaths in children infected with COVID-19 were also very rare, confirming the findings of previous studies.

"There is a lot of anxiety among parents about the risk of COVID-19 in children," said Dr. Kakkar. "It's important to reassure parents. It's not the same disease as in adults. I hope it will allow the children to live a little more normally."

The benefits for children to attend school and have normal friendships, which are critical to their development, far outweigh the risks associated with the disease, she added.

Though the findings of this study, believed to be the first of its kind in Canadian children, are encouraging and reassuring, they should not give parents a false sense of security when it comes to deciding whether or not to vaccinate their children, Dr. Kakkar said, as some healthy children have been hospitalized.

"We don't know which of these healthy children are going to be the sickest and we know that when you have a severe illness, you have sequelae," she said. "A child intubated in the ICU requires months of rehabilitation and unfortunately, we can't predict which child is going to fall into that category."

An unvaccinated child is also more likely to continue to spread the virus among family and friends, Dr. Kakkar said.

She points out the study was done before the emergence of the Delta variant, which is much more transmissible and is taking its toll on unvaccinated adults.

"I don't want to discourage parents from vaccinating their children at all," she concluded. "You really have to look at the total well-being of the child. What will allow him to have a normal life, to do activities, sports, to see friends, is the vaccination."

-- This report by The Canadian Press was first published in French on Sept. 27, 2021.