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Research teams in Montreal, Toronto looking at how COVID-19 impacts immunity

Last Updated Dec 17, 2020 at 2:23 pm CST

FILE -- Specimens to be tested for COVID-19 are seen at a lab, in Surrey, B.C., on Thursday, March 26, 2020. THE CANADIAN PRESS/Darryl Dyck

MONTREAL – Research from two university teams is shedding a little bit of light on why COVID-19 patients have more severe side effects than those with the regular seasonal flu.

The teams, from the Université de Montréal and the University of Toronto are backed by Canada’s COVID-19 Immunity Task Force (CITF). The Toronto team recently had its findings shared in the Journal of Immunology.

Researchers in Toronto took blood cells from 13 people who had recovered from COVID-19 and stimulated them with parts of the virus to see if immune cells would recognize and respond to the SARS-CoV-2 proteins. They also injected other samples with the flu.

“We compared these responses to what we see with the common influenza virus, a virus to which most adults are immune and are exposed to often,” said researcher Tania Watts, professor in the Department of Immunology at the University of Toronto’s Temerty Faculty of Medicine and co-lead on the study.

“All the SARS-CoV-2 recovered patients had immune memory responses to both SARS-CoV-2 and to the influenza virus, but with significant differences in how they responded.”

The samples injected with SARS-CoV-2 showed increased inflammation and a response which, according to the study’s co-lead, implied less protection from infection than when the blood was injected with the regular flu.

“We need to find out whether the immune cells in the blood of someone who has recovered from COVID-19 will react similarly or differently to a vaccine for SARS-CoV-2. Will they have a more inflammatory and less protective response?” said study co-lead Mario Ostrowski, professor in the Departments of Medicine, Immunology, Laboratory Medicine and Pathobiology at the U of T.

“With plans to vaccinate Canadians in full swing, it is important to continue to evaluate how people who previously had COVID-19 will respond to vaccines.”

The team at the Université de Montréal will be looking into whether it can predict which people who fell ill with COVID-19 will have a more severe experience and if survivors can develop long-term immunity.

So far, Quebec researchers found that antibody levels in COVID-19 patients drop rapidly during the weeks after symptoms disappeared.

“We were exploring the use of blood plasma from recovering patients as a possible treatment for patients with severe COVID-19 symptoms,” explained lead author Andrés Finzi, Canada Research Chair and associate professor at the Department of Microbiology, Infectiology et Immunology, Université de Montréal.

“The blood of recovered patients contains antibodies that can act against the SARS-CoV-2 virus. However, our research shows that, if it is shown to have a clear benefit, the convalescent plasma will need to be collected during a specific window of time after recovery. Since recovering patients can’t donate blood until at least 14 days after symptoms have subsided to give the body time to clear viral particles, the window will be tight.”

Initial findings have been published in mBio, an open-access journal of the American Society of Microbiology.

Canada’s top doctor, Dr. Theresa Tam, said the research from these teams will help the government decide how best to target public health responses to the virus.