A blood donor clinic pictured at a shopping mall in Calgary, Alta., Friday, March 27, 2020. Fewer than 1 per cent of Canadian blood donors in late spring tested positive for COVID-19 antibodies, according to the results of a seroprevalence study that aimed to assess the country’s infection rate of the novel coronavirus. THE CANADIAN PRESS/Jeff McIntosh

A blood donor clinic pictured at a shopping mall in Calgary, Alta., Friday, March 27, 2020. Fewer than 1 per cent of Canadian blood donors in late spring tested positive for COVID-19 antibodies, according to the results of a seroprevalence study that aimed to assess the country’s infection rate of the novel coronavirus. THE CANADIAN PRESS/Jeff McIntosh

Study shows fewer than 1 per cent Canadian blood donors had COVID antibodies

Researchers say antibodies indicate past infection

Fewer than 1 per cent of Canadian blood donors in late spring tested positive for COVID-19 antibodies, according to the results of a seroprevalence study that aimed to assess the country’s infection rate of the novel coronavirus.

Canadian Blood Services and Canada’s COVID-19 Immunity Task Force (CITF) released the findings of the study on Tuesday, based on 37,373 blood samples collected from blood donor centres across Canada except Quebec and the Territories from May 9 to June 18.

The results suggest that by the end of May as few as 0.7 per cent of healthy Canadians had been exposed to SARS-CoV-2, the virus causing COVID-19.

Researchers say antibodies indicate past infection, and can usually be detected within two weeks of the onset of infection.

However, they say the results of the study could underestimate “true seroprevalence” for a number of reasons.

Professor Catherine Hankins, the co-chair of CITF, says antibody levels decline rapidly, and “may have disappeared in some people by the time of testing.”

Hankins also says blood donors are typically more ”health-conscious and healthier” than the general population.

CITF co-chair David Naylor says the current increasing number of COVID-19 cases nationwide suggests a need for continued vigilance.

And while health experts are still unclear on how much, if any, immunity antibodies might provide, Naylor says there is “little to no likelihood” that immunity levels in the population are “high enough to slow down a second wave of COVID-19 infection.

“It’s critical to ramp-up testing and tracing capacity across the country to reduce risk in settings such as workplaces and schools, and to interrupt any chains of transmission quickly to prevent spread,” he added.

The results of the study were broken down by province, showing that P.E.I. and New Brunswick had the lowest seroprevalence at 0 per cent and 0.26 per cent, respectively. Ontario showed the highest with 0.96 per cent.

Quebec’s Hema-Quebec ran its own study on blood donors in the province, which showed the highest seroprevalence in the country at 2.23 per cent.

In individual cities, Ottawa showed the highest percentage of SARS-CoV-2 antibodies with 1.29 per cent seroprevalence, Toronto had 1.07 per cent and Edmonton had 0.38 per cent.

Montreal and Laval showed a seroprevalence of 3.05 per cent in the Hema-Quebec study.

Dr. Graham Sher, CEO of Canadian Blood Services, says its donor base is ”reasonably representative of healthy Canadians between the ages of 17 and about 60.”

READ MORE: B.C. records 429 new COVID-19 cases, two deaths over Labour Day long weekend

The Canadian Press


Like us on Facebook and follow us on Twitter.

Want to support local journalism during the pandemic? Make a donation here.

blood donorCoronavirus

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

A cougar was spotted at Royal Roads University on Sunday, Jan. 24. The sighting was reported on the western edge of the campus. (File photo)
Cougar spotted at Royal Roads University Sunday afternoon

Animal reported on western side of campus near Langford Fire Department

The Habitat for Humanity Meaning of Home contest is open to students in Grades 5 to 6. (Screenshot/Habitat for Humanity video)
Habitat for Humanity launches national writing contest

Entries accepted from students in Grades 4 to 6 until Feb. 19

Colwood Fire Rescue is reminding the public to only burn dry, seasoned wood in fireplaces after heavy smoke filled the intersection of Sooke Road and Acacia Drive when a homeowner tried burning a plastic item on Sunday, Jan. 24. (Emily Jessop photo)
Colwood homeowner burns plastic in fireplace, causes emergency response

Colwood Fire Rescue says burn dry, seasoned wood in fireplaces only

A rolled-over car was spotted in a ditch along Sooke Road near the border of Langford on the morning of Sunday, Jan. 24. (Black Press Media photo)
Car ends up in ditch along Sooke Road Sunday morning

Single vehicle spotted rolled-over just after 10 a.m. on Jan. 24

Terrance Josephson of the Princeton Posse, at left, and Tyson Conroy of the Summerland Steam clash during a Junior B hockey game at the Summerland Arena in the early spring of 2020. (John Arendt - Summerland Review)
QUIZ: How much do you know about hockey?

Test your knowledge of Canada’s national winter sport

Wet’suwet’en supporters and Coastal GasLink opponents continue to protest outside the B.C. Legislature in Victoria, B.C., on Thursday, February 27, 2020. THE CANADIAN PRESS/Chad Hipolito
‘We’re still in it’: Wet’suwet’en push forward on rights recognition

The 670-km Coastal GasLink pipeline was approved by B.C. and 20 elected First Nations councils on its path

The sky above Mt. Benson in Nanaimo is illuminated by flares as search and rescuers help an injured hiker down the mountain to a waiting ambulance. (Photo courtesy Nanaimo Search and Rescue)
Search plane lights up Nanaimo mountain with flares during icy rope rescue

Rescuers got injured hiker down Mt. Benson to a waiting ambulance Saturday night

Jennifer Cochrane, a Public Health Nurse with Prairie Mountain Health in Virden, administers the COVID-19 vaccine to Robert Farquhar with Westman Regional Laboratory, during the first day of immunizations at the Brandon COVID-19 vaccination supersite in Brandon, Man., on Monday, January 18, 2021. THE CANADIAN PRESS/Tim Smith - POOL
Top doctor urges Canadians to keep up with COVID measures, even as vaccines roll out

More than 776,606 vaccines have been administered so far

From the left: Midway RCMP Csts. Jonathan Stermscheg and Chris Hansen, Public Servant Leanne Mclaren and Cpl. Phil Peters. Pictured in the front are Mclaren’s dog, Lincoln and Peters’ dog, Angel. Photo courtesy of BC RCMP
B.C. Mounties commended for bringing firewood to elderly woman

Cpl. Phil Peters said he and detachment members acted after the woman’s husband went to hospital

Dr. Jerome Leis and Dr. Lynfa Stroud are pictured at Sunnybrook Hospital in Toronto on Thursday, January 21, 2021.THE CANADIAN PRESS/Frank Gunn
‘It wasn’t called COVID at the time:’ One year since Canada’s first COVID-19 case

The 56-year-old man was admitted to Toronto’s Sunnybrook Health Sciences Centre

An Uber driver’s vehicle is seen after the company launched service, in Vancouver, Friday, Jan. 24, 2020. Several taxi companies have lost a court bid to run Uber and Lyft off the road in British Columbia. THE CANADIAN PRESS/Darryl Dyck
Taxi companies lose court bid to quash Uber, Lyft approvals in British Columbia

Uber said in a statement that the ruling of the justice is clear and speaks for itself

Nanaimo Regional General Hospital. (News Bulletin file photo)
COVID-19 outbreak declared at Nanaimo hospital

Two staff members and one patient have tested positive, all on the same floor

A long-term care worker receives the Pfizer vaccine at a clinic in Nanaimo earlier this month. (Island Health photo)
All Island seniors in long-term care will be vaccinated by the end of this weekend

Immunization of high-risk population will continue over the next two months

Most Read