A boy wearing a mask looks at a book in a classroom

Regularly randomly testing students for COVID-19 could help control outbreaks in schools and allow them to remain open, reveals a new study involving a University of Guelph researcher.

The study, published recently in BMC Public Health, found testing one to two students a day in every classroom could be an effective way to keep transmission rates in schools stable.

Dr. Monica Cojocaru, study co-author and a professor in U of G’s  Department of Mathematics and Statistics, said while schools have relied on physical distancing and masks, conducting more COVID-19 testing is key to keeping schools open.

“We know that school closures hurt everyone – children, parents, teachers, the economy. We need to be using testing as a tool in this fight. But we need to have a strategy for that testing and that’s what this study aimed to propose,” she said.

The study was led by York University collaborators Profs. Ali Asgary and Jianhong Wu, and post-doctoral researcher Dr. Mahdi M. Najafabadi, who devised the individual simulated model of school testing. Cojocaru developed the theoretical validation for the simulation tool that aimed to analyze the effectiveness of testing strategies amid different school scenarios.

They aimed to determine how much testing would be needed to keep the “effective reproductive number” at or below one, meaning transmission would not increase but remain at least at the current level.  For the model, the researchers assumed that any student who tested positive would go into self-isolation at home.

A photo of Dr. Monica Cojocaru
Dr. Monica Cojocaru

Based on a school with 500 students with 20 classes of 25 students, the researchers found that with no other control measures, testing every student every 10 days would avoid school outbreaks. That would mean testing three students a day in every class.

They then ran their calculations under the scenario of students wearing masks, which would reduce transmission risk by 30 to 80 percent, depending on the mask and mask-wearing compliance.

In that scenario, the number of students needed to be tested in each class every day would drop to roughly 1.5, which would mean 900 tests a month.

The researchers concluded that regular testing of students can control infections if tests are done frequently and processed quickly, so long as infected students can self-isolate at home.

“Our simulation results for testing of SARS-CoV-2 in Ontario schools shows it can be an effective method for controlling outbreaks,” said Asgary, a professor in York’s Faculty of Liberal Arts & Professional Studies and associate director of the Advanced Disaster, Emergency and Rapid Response Simulation. “It won’t eliminate the risk of infection, but it can be a powerful tool.”

While vastly increasing testing capacity has challenges and costs, implementing and enforcing lockdowns is also expensive, said Cojocaru.

“Testing should be used as an active control measure rather than as a reactive approach,” said Cojocaru. “We shouldn’t just test those who we suspect are already infected. We need to find those who are pre-symptomatic or asymptomatic.”

She added that the model and random-testing concept could also be applied to businesses, manufacturing facilities, long-term care facilities and elsewhere.

“If we can redirect our current testing approach to optimize our priorities – such as our school and essential services – we could gain greater control of this pandemic while we wait for vaccines and avoid very stringent lockdowns.”

This research was funded in part with a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC).


Dr. Monica Cojocaru