Canadian study confirms children and youth at low risk of severe COVID-19 during first part of pandemic

OTTAWA – A study by the Canadian Paediatric Surveillance Program (CPSP) has shown that children-- particularly pre-school and school-aged children--were at low risk of severe COVID-19 disease in the first part of the pandemic. This work, published in the Canadian Medical Association Journal (CMAJ) on September 27th represents the largest study of hospitalized children and youth infected with SARS-CoV-2 in Canada.

SARS-CoV-2 is the virus which can develop into COVID-19 disease. People can test positive for SARS-CoV-2 but may not develop COVID-19 (asymptomatic).

The landmark study, conducted from April to December 2020, aimed to describe the characteristics of children and youth hospitalized with SARS-CoV-2 infection, as well as to identify risk factors for severe COVID-19 disease among hospitalized children and youth. This study was conducted before the Delta variant was introduced into Canada. 

While nearly 34,000* Canadians (of all ages) with SARS-CoV-2 were admitted to hospital during the same period, only 264 children and youth were reported to the surveillance program. The majority of these cases were in Ontario and Quebec, Canada’s most populous provinces. Just over half (56.8%) of children and youth reported were admitted specifically for COVID-19 disease. In the remaining cases, children and youth were in hospital for reasons other than COVID-19, such as a fracture, and were found to have SARS-CoV-2 upon routine screening (so-called “incidental infections”).

“When we started this study in March 2020, we were uncertain what to expect,” says Dr Shaun Morris, co-senior author and one of the Principal Investigators (PIs), staff physician in the Division of Infectious Diseases and scientist in the Child Health Evaluative Sciences program at The Hospital for Sick Children (Sick Kids).

Dr Morris says he was concerned that young children “would be among the higher risk groups,” tracking with other respiratory infections. Instead, the risk for severe disease and death was low.

“This was unexpected. We saw a large mortality spike in the elderly but not in the very young.”

Dr. Olivier Drouin, the study’s first author and clinician in the Department of Paediatrics at Montreal’s Sainte-Justine University Hospital Centre (CHU Sainte-Justine), described the results as “reassuring”. He said investigators didn’t expect the number of children and youth requiring hospital or ICU admission to be “so low.”

“The study is unique in that detailed information on each case was collected,” says Dr. Fatima Kakkar, co-senior author and PI, from the Division of Infectious Diseases at Sainte-Justine. With this detailed information, researchers were able to identify a number of risk factors for more severe disease among children and youth hospitalized with COVID-19.

Overall, 39.3% of children and youth hospitalized for COVID-19 had at least one co-morbidity. Children and youth with severe disease were more likely to have an underlying health condition such as obesity, neurological and respiratory conditions (other than asthma).

“Overall, the results of this study serve to inform parents and policymakers that severe acute disease in kids was rare during the study period,” says Dr Morris.

The Canadian Paediatric Surveillance Program (CPSP) is a longstanding partnership between the Canadian Paediatric Society and the Public Health Agency of Canada (PHAC). The program engages 2800 paediatricians and paediatric subspecialists, representing the vast majority of paediatric providers in the country.

“Investing in stable public health infrastructure allows for the rapid collection of detailed, real-time data to help inform clinical decision-making and public health policy,” says Dr. Charlotte Moore Hepburn, one of the study’s PIs and the Director of Medical Affairs for the Canadian Paediatric Society.

“Canada is fortunate to have this infrastructure in place, as it allows for the efficient collection of critical data in both pandemic and non-pandemic times.”

The investigators are continuing to monitor hospitalizations associated with SARS- CoV-2 in children and youth, and will be closely monitoring the impact of the Delta variant on the paediatric population. 

Key messages:

• This publication represents the largest Canadian study on children and youth hospitalized with SARS-CoV-2 infection from the  start of the pandemic through December 2020.
• Children are at low risk of severe disease from COVID-19.
• The least reported cases were among pre-school (1-5) and school-aged (6-12) children.
• Almost half of all children and youth admitted to hospital with SARS-Co-V-2 were admitted for reasons unrelated to COVID-19 (for example, fracture, surgery).
• Risk factors for severe disease among those hospitalized with COVID-19 included obesity, neurological and respiratory conditions (other than asthma).
• Public health surveillance infrastructure (including the Canadian Paediatric Surveillance Program) enabled the rapid, real-time collection of critical clinical and public health data.
• Ongoing surveillance is necessary to understand the impact of the Delta variant on Canadian children and youth.

*Data from the Public Health Agency of Canada and Statistics Canada

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For more information or to schedule an interview, please contact:

media@cps.ca

Jessamine Luck
Senior Communications Adviser
The Hospital for Sick Children
Jessamine.Luck@sickkids.ca

Florence Meney
Senior Communications Adviser
CHU Sainte Justine
Florence.Meney.hsj@ssss.gouv.qc.ca

Kim Barnhardt
Senior Strategist, Communications & Partnership
CMAJ.CA
Kim.Barnhardt@cmaj.ca