Health Canada will allow men to donate blood if they haven't had sex with a man in the last five years, a change in policy that will go into effect in the coming weeks.

"If a man has not had sex with another man within the last five years and meets all the other eligibility criteria to be a blood donor, he will be able to donate blood," Dana Devine, who is vice-president of medical, scientific and research affairs at Canadian Blood Services, told reporters Wednesday from Vancouver.

"This is a very significant change for us."

Canadian Blood Services and Hema Quebec submitted scientific data on how disease-causing agents in blood donations are screened and detected rapidly, Health Canada says. (Jorge Dan/Reuters)

Previously, men who said they had sex with a man, even once, since 1977, were not eligible to donate blood.

Devine called it a prudent first step to make until the blood agency collects and analyzes data on HIV incidence in prospective donors as part of its review of further reductions to the deferral period.

Health Canada now says advances in screening technology mean disease-causing agents are more easily and quickly detected.

The changes take effect by the summer, Canadian Blood Services said, to allow time to adjust screening procedures.

Australia and the United Kingdom have reduced their lifetime bans.

Both Canadian Blood Services and Héma-Québec requested the five-year deferral, Devine said. Health Canada answers such requests with a yes or no answer, she said.

Devine acknowledged the length of the deferral won't satisfy everyone. "Bear with us."

Lawyer Adrian Lomaga of Toronto launched a lawsuit against Héma-Québec when he was student at McGill University in Montreal. Lomaga said he dropped the case after he was promised that the blood agencies would ask Health Canada for a change in the policy.

"The scientific evidence doesn't warrant a lifetime deferral period," Lomaga said in an interview.

"I will not be able to give blood, but I'm hopeful that in the future, with further advances in the science and the technology available, that one day I will be able to be a blood donor. That's my goal."

On Toronto's Church Street, which is adorned with rainbow-coloured flags, Ian Mahaffy said he still considers the policy discriminatory.

"It just doesn't make any sense," Mahaffy said. "If you're gonna lift the ban, lift the ban. And treat everybody equally, the same. Whether you're gay, straight, whatever, the fact is it should be going under the same scrutiny as everyone."