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Registered nurse Florisa N. Lingad prepares a dose of a Johnson & Johnson Covid-19 vaccine at a vaccination center established at the Hilton Chicago O'Hare Airport Hotel in Chicago, Illinois, on March 5, 2021.

KAMIL KRZACZYNSKI/AFP/Getty Images

Canada now has a fourth make of vaccine to deploy against the COVID-19 pandemic – or fifth depending on how you count. But whether that will shift the needle on getting the country immunized will depend crucially on production and delivery schedules over the next few months.

On Friday, Health Canada regulators announced they have authorized the single-dose vaccine from the Janssen Pharmaceutical Companies, owned by Johnson & Johnson. The decision comes just days after the U.S. Food and Drug Administration approved the vaccine, and one week after Canada gave the green light to a vaccine produced by AstraZeneca and a nearly identical product from the Serum Institute of India.

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Like the two versions of the AstraZeneca vaccine, the Johnson & Johnson shot can be kept at refrigerator temperatures. That frees it from the constraint of transportation and storage in frozen form that the Pfizer and Moderna vaccines require. And because the Johnson & Johnson vaccine is the first to be administered in a single dose, it may be a game changer for vaccinating people who do not have easy or regular access to health care.

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“This promises greater flexibility for Canada’s vaccine rollout,” Supriya Sharma, chief medical adviser at Health Canada, said at a news briefing.

This essentially means Canada has approved four different vaccines, although federal officials referred to the AstraZeneca product and its made-in-India counterpart as separate.

Johnson & Johnson’s agreement with Canada includes 10 million doses by the end of the third quarter of 2021, but it is not clear when the first may arrive.

Federal officials said they are still confirming delivery schedules with Johnson & Johnson and AstraZeneca.

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On Friday, Prime Minister Justin Trudeau announced a significant increase to the number of Pfizer shots expected this spring. Canada will now get a total of 5.5 million doses from Pfizer before the end of March. The increase means Canada will receive eight million shots before April, rather than six million. Even before accounting for deliveries from Johnson & Johnson and AstraZeneca, Canada will receive a cumulative 36.5 million doses by the end of June. That alone would be enough to cover at least a first shot for everyone in the country who is eligible to receive one.

“We are expecting far more doses by September than there are Canadians,” Mr. Trudeau said. “It is possible that we have further good news and good predictions to share in the coming weeks.”

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Syringes loaded with doses of the Johnson & Johnson COVID-19 vaccine sit on the table at a vaccination centre established at the Hilton Chicago O'Hare Airport Hotel in Chicago on March 5, 2021.

KAMIL KRZACZYNSKI/AFP/Getty Images

Including the expected deliveries from all authorized vaccines, Canada will receive 117.9 million shots by the end of September, Procurement Minister Anita Anand said on Friday.

The Johnson & Johnson vaccine has been authorized for people 18 years and older.

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While regulators made the same determination for the AstraZeneca vaccine, an independent expert panel said it did not recommend that vaccine be used for anyone 65 and older because of a paucity of data from that group in clinical trials. The panel is expected to begin forming recommendations for the Johnson & Johnson vaccine next week.

Dr. Sharma said data available from the Johnson & Johnson clinical trial, which included more than 40,000 people, cover age groups that include seniors, who made up about 20 per cent of the study.

“The results from those groups showed that the efficacy … and the safety profile was actually very similar in that 65 and older group.”

Overall, the clinical trial data show the Johnson & Johnson vaccine has as average efficacy of 66 per cent at preventing COVID-19, and 85 per cent at preventing the severe form of the disease. Once immunity was well established about 28 days after the shot, no trial participants who received the vaccine were admitted to hospital or died of COVID-19.

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Dr. Sharma said that while trial results differ for the vaccines that have now been authorized, “the reality is that you will have a greatly reduced chance of getting COVID-19” with any of them.

Ebele Ola, a physician and vice-president of medical affairs for Janssen in Canada, noted that the company held its vaccine trial in multiple regions of the globe, including South Africa and Latin America, where variants of the virus that causes COVID-19 are more prevalent and may have reduced the average efficacy. In the U.S. part of the trial, which may be a better comparison for Canada, the efficacy of the vaccine was found to be 72 per cent.

Dr. Ola said she could not yet say where the doses of the vaccine for Canada would be made but added “we are going to leverage our global supply.”

The vaccine delivers genetic information about the coronavirus into human cells using a different type of virus, called an adenovirus, as the carrier. Once administered, the vaccine triggers the production of coronavirus proteins which, in turn, stimulate the immune system to recognize and fight the coronavirus.

Zhou Xing, a McMaster University researcher who specializes in adenovirus vaccines, said the Johnson & Johnson product, like AstraZeneca’s, may do well at stimulating “killer” immune cells that eliminate other cells that have been infected with the coronavirus, rather than simply promoting antibodies that block infection. That might account for why the vaccine’s efficacy improves against more severe forms of the disease, he said.

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He added that the ability of the Johnson & Johnson vaccine to perform with a single dose suggests AstraZeneca’s might fare just as well. Johnson & Johnson is also conducting a trial to test whether the performance of its vaccine is improved with a second dose after six weeks.

Amine Kamen, an expert in the production of viral vaccines at McGill University, said the National Research Council biomanufacturing centre now under construction in Montreal could, in principle, make the Johnson & Johnson vaccine if licensed to do so.

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Editor’s note: A previous version of this story incorrectly named a McMaster University researcher Xiao Zhou. The current version uses the correct name, Zhou Xing. The Globe regrets this error.