A closer look at the vaccines Canada is betting on to stem the spread of COVID-19 Social Sharing

Canada has announced that it has signed deals with four U.S. companies to reserve millions of doses of COVID-19 vaccines under development in an effort to make sure Canadians are at “the front of the line” when a vaccine becomes available.

The federal government announced agreements with Moderna and Pfizer/BioNTech on Aug. 5 and with Novavax and Janssen, a subsidiary of Johnson & Johnson, earlier this week.

It also said it’s close to a deal with AstraZeneca, based in the United Kingdom.

All of the companies have received funding from the U.S. government’s Operation Warp Speed, which is investing billions of dollars to fast-track the development of promising vaccine candidates.

Canada will receive 20 million to 76 million doses of each vaccine, should any of them successfully make it through clinical trials and be approved by Health Canada.

They’re among more than 150 vaccine candidates under development around the world.

While they have shown promising results in small-scale, early-stage clinical trials, even those most advanced candidates have only recently begun Phase 3 clinical trials to determine their effectiveness in preventing COVID-19, and there is no guarantee any of them will make it to market. That’s the crucial large-scale human trial that must demonstrate that the vaccine prevents the disease, and it’s the final stage before approval by government.

“What we don’t know, of course, is which vaccines are going to be effective,” Dr. Michael Gardam, medical director of infection prevention and control at Toronto’s Women’s College Hospital, said in an interview with CBC’s As It Happens.

“We don’t know which company ultimately is going to have the best vaccine and the safest vaccine.”

Gardam said the deals represent different types of vaccine from four different manufacturers. The federal government, he said, is “just kind of playing the field … to make sure they have a reasonable chance that one of these will be successful.”

Here’s a closer look at the four candidates.

Janssen Pharmaceutical Companies (Johnson & Johnson)

Headquarters: Raritan, N.J., U.S.

Type: Non-replicating viral vector

Doses reserved: Up to 38 million

Phase of development: Phase 1/2a trial started in July

How it works: This vaccine, made by a Johnson & Johnson subsidiary, is a new type of vaccine called a non-replicating viral vector. Unlike traditional vaccines made from viruses or parts of viruses, this vaccine uses only a piece of coronavirus DNA. The DNA contains instructions for making a coronavirus protein so that the human body can produce it and learn to recognize it.

The protein targeted by most COVID-19 vaccines, including this one, is called the spike protein or S-protein. It’s found on the outer surface of coronaviruses and is used by the virus to bind to and enter human cells.

In this case, the DNA with instructions for making the spike protein is carried into the body by a common cold virus called an adenovirus. The adenovirus has been genetically modified so it can’t replicate itself in the human body. However, because it’s a virus, it may generate a stronger immune response than the DNA alone and helps get the DNA into human cells, where the spike protein can be produced. One disadvantage of this type of vaccine is that some people may have immunity to some adenoviruses from catching colds, which may make the vaccine less effective.

Viral vector vaccines haven’t been approved for widespread use in humans, but 12 are in use for diseases in livestock.

Where it’s at: The company reported in July that its vaccine protected monkeys against the virusafter a single shot. The company started a human Phase 1/2a trial in July in Belgium and the U.S, and it announced this week it is starting a Phase 2 trial in Spain, the Netherlands and Germany. It says it will conduct Phase 3 trials in Argentina, Brazil, Chile, Colombia and Mexico.

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