One-third of COVID-19 cases in Ont. children asymptomatic, U of G study finds
KITCHENER -- A study by researchers at the University of Guelph found that more than one-third of COVID-19 cases among children in Ontario were asymptomatic.
Researchers said this shows the need for targeted testing to find asymptomatic and mild infections to prevent spread of the disease.
The study, which was led by Dr. Ed McBean, looked at data from nearly 220,000 positive cases in the province over the past year.
“This is worrisome as undocumented COVID-19 cases in children could cause the rapid spread of silent COVID-19 transmission in communities,” McBean said in a news release posted on the university's website.
According to researchers, 35 per cent of children under nine were asymptomatic, and 31 per cent only had one symptom. The most common symptom, found in 30 per cent of children under nine, was a fever. They also said cases tended to be milder in children and very few had a cough.
“Our findings indicate that asymptomatic and pre-symptomatic cases are substantial in number,” said McBean in the release. “This highlights the importance of targeting asymptomatic and mild infections in the continuing effort to control the spread of COVID-19.”
The study was published in Infectious Disease Reports. The data came from 219,075 cases from 8.4 million COVID-19 tests performed between January 2020 and January 2021. It was all provided by the Ministry of Health. The researchers classified positive tests by symptoms, which included cough, fatigue, fever, shortness of breath, headache and sore throat. There was also a category for no symptoms.
“There is a broad range of severity of illnesses from COVID-19 making asymptomatic infections important to understand because the virus can still be transmitted causing critical illness in others,” McBean said.
McBean said asymptomatic testing is still important during the stay-at-home order.
“Given the fact that more than 30 per cent of children with the virus are asymptomatic, it would be effective to invest in testing to identify asymptomatic children in situations where children are not wearing masks, such as in daycares, and are in close proximity to other children or adults such as multi-generational homes and daycares," he said.
Schools across the province closed indefinitely after April break.