TORONTO -- Health Canada has approved the Moderna COVID-19 vaccine for use in this country with the first doses expected to be delivered by Christmas.

Canada is now the second country in the world after the U.S. to approve the Moderna shot, the second coronavirus vaccine to get the green light in the country’s mass immunization effort. Two weeks ago, the federal health agency approved the Pfizer-BioNTech vaccine.

Health Canada has deemed the Moderna vaccine effective and safe for use on Canadians, which means deliveries of the first set of doses will begin imminently, weeks faster than the original timeline to receive shipments in January.

“Canada has an internationally recognized process of independent review, and I know that our best experts have upheld this highest standard,” Prime Minister Justin Trudeau said during a Wednesday afternoon news conference. “Now that Health Canada has approved the Moderna vaccine, we have the green light to start rolling it out across the country.”

Trudeau has said previously that Canada will receive up to 168,000 doses of the vaccine this month, with deliveries arriving between 24 and 48 hours after approval, as per the government’s contract with the U.S. biotech company.

“We know that this pandemic doesn't start to end until we have vaccination of millions and millions of people which is why we're continuing to ensure that everything is done safely and responsibly, to make those vaccines available as quickly as possible and we all look forward to things being much better in the spring,” Trudeau said.

Trudeau added that Canada is expected to have acquired 1.2 million doses of the two approved vaccines by the end of January, but Canada’s COVID-19 Immunity Task Force is still working with Pfizer and Moderna to confirm how many doses of each it will have by that timeframe.

“We have a number of planning assumptions for that, and moving forward in terms of both Moderna and Pfizer products, and we're working actively to confirm those planning assumptions, turn them into facts as we move forward,” Maj.-Gen. Dany Fortin, the top military general in charge of Canada’s vaccine distribution, told reporters on Wednesday.

Fortin added that while the government expects more than a million doses by the end of January, he expects the rollout to really ramp up in the subsequent months.

“I anticipate a significant growth in quantities available in February (and) March,” he said. “I would be speculating as to what exactly that looks like, but as I indicated before, we have daily conversations with the manufacturers, and we will increase this frequency with Moderna as well.”

In total, Moderna has promised 40 million doses to Canada by the end of 2021.

“Today’s authorization is one more tool in our toolbox to bring COVID-19 under control,” Dr. Supriya Sharma, the chief medical advisor for Health Canada, said at a press conference in Ottawa on Wednesday.

It's another crucial moment in the fight against the novel coronavirus as each vaccine candidate comes with its own unique set of advantages and barriers. The Pfizer-BioNTech vaccine, which is already in the arms of thousands of Canadians, needs to be kept at temperatures between -60 C and -80 C until injection, while the Moderna vaccine can be kept stable at just -20 C.

'THE WORKHORSE VACCINE'

“The elephant is in the room that the Moderna vaccine is coming and probably the rollout of that vaccine is really going to change the landscape more than anything else,” Dr. Zain Chagla, an infectious disease specialist and associate professor at McMaster University, told CTVNews.ca during a phone interview on Wednesday.

“You don’t have to set up a clinic right beside where you have these ultra-cold fridges,” he said. Instead, health-care workers can administer the Moderna vaccine bedside in long-term care homes, he said. And the immunization task force can likely deliver the Moderna shots to small rural hospitals and remote northern regions that couldn’t facilitate the freezer requirements of the Pfizer product.

More Canadians are likely to get the Moderna vaccine than the Pfizer one, he added.

“This is the game-changer vaccine for sure,” he said. “For our long-term strategy for vaccinating all Canadians, the Moderna is probably going to be the workhorse vaccine. The Pfizer will probably be a vaccine in urban centres, in places where they’re able to set up the clinics that can do the Pfizer vaccine.”

WHO WILL GET IT AND WHEN?

Health Canada has approved the Moderna vaccine for use in Canadians aged 18 and older, but it will likely be many months before healthy adults who are not on the front lines get inoculated and still “several days” before the most vulnerable receive the shot, said Dr. Ronald St. John, the first Director-General of the Centre for Emergency Preparedness and Response at the Public Health Agency of Canada. While the Moderna shipments are coming this week, it’s just the first step in a logistical process, he told CTV News Channel.

“The plane arrives at the airport but then there’s a couple of steps, quite a few steps that have to take place from the airport to eventually end up in somebody’s arm,” he said. After Health Canada approved the Pfizer vaccine on Dec. 9, it took another four days for the first shipment to land in Canada on Dec. 13, and another day before the first health-care workers were immunized.

As with the Pfizer vaccine, the Canadian government’s immunization task force has outlined which Canadians will be at the front of the line for the Moderna shot, including health-care workers and vulnerable people in long-term care facilities.

To boost the immunization effort, the Canadian government has set up another 56 distribution sites (in addition to the 14 already operating) to administer doses to the prioritized groups.

“We're going to grow the number of sites as we get more stability data and we're able to further distribute down from those sites to additional sites,” Fortin said. “There'll be a better spread.”

It is expected that the territories will receive more than the per capita percentage of Moderna vaccines since officials made the decision not to send the Pfizer shots to the North, where they lack the necessary ultra-cold storage capabilities. This time, the territories are well-equipped.

Last week, the Canadian Armed Forces delivered to the territories five freezers that can keep the Moderna doses stable at -20 C.

“With the unique situation in the North, the isolated communities, lack of access to let's say tertiary health-care facilities and so on, the planning sort of assumption has been to really deliver enough vaccine to be able to cover 75 per cent of their population, so that we're not making multiple trips to a small community,” said Dr. Howard Njoo, Canada’s deputy chief officer of public health.

“I think it's really in a sense, get it all up there and then they can start vaccinating their populations as a whole.”

Fortin added shipments of the vaccine are expected to arrive in the territories beginning on Monday.

MODERNA VS. PFIZER

Both the Moderna and Pfizer shots are messenger RNA vaccines, which send a genetic code to cells to train them to develop an immune response to COVID-19. Early data suggests both are more than 90 per cent effective at fending off the virus, including strains that Health Canada said on Wednesday were “similar” to the new U.K. variant identified this month.

While the two products have much in common, one of the key differences is in their distribution plans. While Pfizer has been shipping its own vaccines with UPS, Canada will be in charge of getting the Moderna shipments across the country once they are delivered and have contracted Innomar Strategies and FedEx Express Canada to do the job. Earlier this month, officials confirmed that FedEx Express Canada and Innomar will be picking up Canada’s Moderna doses in Europe, where they have been kept on dry ice with temperature-monitoring devices. They will be flying them to a central location in Canada from where the allotments for each region will be distributed. The vaccines will be kept at Innomar distribution facilities across the country, including a 160,000-square-foot space in Ontario, all of which have controlled-temperature storage capabilities as low as -25 C, colder than required for the Moderna vaccine.

“Innomar will safely and securely store the vaccines in its storage facilities, which are equipped to store complex pharmaceutical products,” said a statement from Innomar on Wednesday. “Before the vaccines are shipped, teams will put the vaccine in packages that support the temperature requirements specified by the manufacturer.”

SPEED CONCERNS

While some Canadians have expressed concern about the unprecedented speed with which COVID-19 vaccines have been approved, health experts continue to stress that corners were not cut and standards were not lowered. The latest Health Canada safety assessment began on Oct. 12, when Moderna submitted its candidate for evaluation and a number of steps before that were done in parallel, said Dr. Hassan Masri, an associate professor of medicine at the University of Saskatchewan.

“Canada has one of the highest most stringent requirements [for vaccine approval],” he told CTV News Channel on Wednesday. “Why this vaccine was approved more quickly and developed quicker is because all the phase one, phase two, phase three [steps] were happening simultaneously. All the red-taping and bureaucracy were eliminated, and there was a lot of funding for this.”

Health Canada officials stressed on Wednesday that the agency’s standards were maintained throughout the “rolling review” of the vaccine.

“Although this process was completed in a shorter time frame, Health Canada’s rigorous standards were upheld,” Dr. Sharma said in Ottawa on Wednesday. “Under an interim order, Health Canada allows vaccine manufacturers to submit data to us as it becomes available and for Health Canada experts to start the review process right away.”

Moderna has agreed to a set of terms and conditions on the vaccine’s approval that include continuing to provide Health Canada with information about the shot’s safety, effectiveness and quality.

While the new vaccine approval has been called a “game-changer” in Canada’s COVID-19 fight, the country is still in the midst of a worsening surge of coronavirus infections with many regions entering stricter lockdowns this month.

“While there is a light at the end of the tunnel, we know that there are still challenges ahead,” said Dr. Sharma. “We must all do our best to continue following public health guidelines this holiday season and in the new year.”

With files from CTV News Ottawa’s Rachel Aiello, CTVNews.ca Writer Ben Cousins and The Canadian Press