Blood samples collected from tens of thousands of Canadians will soon be tested for signs of COVID-19 antibodies as the federal government seeks to learn how many people have already contracted the novel coronavirus.

Dr. Teresa Tam, chief public health officer for Canada, says Ottawa's immunity task force is collaborating with Canadian Blood Services and Hema-Quebec on the project.

The federal government today announced a contract is now in place with Abbott Laboratories to buy 140,000 serological tests for the project.

The blood tests can detect the presence of the antibody that is produced after a person is infected with the strain of coronavirus that causes COVID-19.

Health Canada authorized Abbott's serology tests on May 21 but negotiations to buy them for use by the immunity task force have taken several more weeks.

Since COVID-19 testing was limited to specific people in most provinces for months, and because some people can get the virus without showing any symptoms, the immunity tests are needed to get a more accurate number of how many Canadians have already contracted it.