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Pfizer and BioNTech announced Monday that their vaccine candidate is 90 per cent effective at preventing COVID-19, based on interim data from a Phase 3 clinical trial.The Associated Press

Results from clinical trials in the United States and Canada have bolstered Ottawa’s hopes of having a COVID-19 vaccine available for some Canadians early next year, with the possibility of a home-grown vaccine ready by the end of 2021.

On Monday, the pharmaceutical companies Pfizer Inc. and BioNTech announced that their vaccine candidate is 90 per cent effective at preventing COVID-19, based on interim data from a Phase 3 clinical trial conducted in the United States.

The trial, which involves more than 43,000 participants, is not yet completed, but it is the first of any vaccine to yield results in Phase 3, the stage that measures how effective it is. The vaccine is among those that the Canadian government has arranged to buy, pending regulatory approval by Health Canada.

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Experts caution that data supporting the Pfizer-BioNTech announcement have not yet been released, and the vaccine could turn out to be less effective as the trial continues. But with cases surging and the prospect of a grim winter ahead, the development is the best indication yet that the pandemic can eventually be brought to heel.

“We see the light at the end of the tunnel,” Prime Minister Justin Trudeau said during a news briefing on Monday. “We hope to see vaccines landing in the early new year."

Mr. Trudeau said that until a vaccine is widely available it is “really, really important that we double down on our efforts" to control the spread of the virus.

Meanwhile, Quebec-based Medicago Inc., which is developing Canada’s leading vaccine candidate, has posted the results of its Phase 1 clinical trial, the first for any COVID-19 vaccine conducted in Canada.

On Tuesday, the company said that all of the 180 subjects in the trial who received the vaccine in two doses developed a significant antibody response to the virus, including those who got the lowest dose. The trial included men and women between the ages of 18 and 55. None of the subjects experienced serious side effects, although some reported mild to moderate effects of short duration.

“That tells us that we’re really in a good spot to move forward and to continue clinical evaluation,” said Nathalie Landry, the company’s vice-president of scientific and medical affairs.

Medicago is set to begin a Phase 2 trial this month and will seek hundreds of volunteers at study sites in Canada, including a cohort of seniors, to examine the performance of the vaccine among those who are at higher risk of experiencing a severe case of the disease. At the same time, the company is planning to launch a Phase 3 trial involving up to 30,000 people in Canada and the United States starting in December.

Prime Minister Justin Trudeau expressed optimism about early results for a new COVID-19 vaccine developed by Pfizer, saying there is now 'light at the end of the tunnel' when it comes to the pandemic.

The Canadian Press

Last month, the government announced it has ordered 76 million doses of Medicago’s vaccine – enough to vaccinate everyone in the country. It has also allocated $173-million to support the vaccine’s development, some of which will go toward the construction of a new production site in Quebec City.

The addition of the Canadian-made vaccine to the government’s list of purchase agreements may prove crucial if competition from other countries limits access to international vaccines. Last month, Dr. Landry said that depending on results of the Phase 3 trial, the Medicago vaccine could be available by the fall of next year.

However, experts hope that Canadians – particularly those at elevated risk from COVID-19 – will not have to wait that long.

“The first candidate vaccines that Canadians will be able to access will be international,” said Mark Lievonen, former president of Sanofi Pasteur Ltd. and co-chair of the federal vaccine task force that provided recommendations to the government about which COVID-19 vaccines to pursue.

Based on those recommendations, Canada has ordered 20 million doses of vaccine from Pfizer. Deals have also been struck with five other companies for more than 250 million doses in total. That is far more than Canada would need if all of the vaccine candidates pass through clinical trials and are approved, an outcome that is by no means guaranteed.

Even then, it remains unclear how long the effects of any vaccine will persist and how frequently people may need to be vaccinated to maintain protection against COVID-19.

“We want vaccines as soon as possible ... but we have to have a view to the next winter and the winter after that,” said Joanne Langley, a professor and infectious disease researcher at Dalhousie University who is the other co-chair of the task force.

In the event that Canada is oversupplied, excess vaccines should be sent to other countries in need, Mr. Lievonen said. Vaccinating the entire globe against COVID-19 will require a massive, multiyear effort – one that may have to adapt if the virus changes in a way that makes some vaccines less effective over time.

It may also turn out that some of the vaccines will be better suited to some of the priority groups the National Advisory Committee on Immunization identified last week, including older people and front-line workers. This could influence provincial and regional plans that are now taking shape – including a task force Toronto launched on Monday to help prepare Canada’s most populous city for a massive vaccination effort.

Dr. Langley added that preparing for vaccines must go hand in hand with maintaining public-health measures that are known to prevent COVID-19.

“Vaccines are coming,” she said. “But we just have to be in it for the long haul to protect our fellow citizens.”

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