TORONTO -- Saturday's announcement that Health Canada has given the green light to a clinical trial for a potential COVID-19 vaccine is welcome news, but there is still a long way to go before any possible treatment becomes a reality.

"Under normal conditions, those types of studies … can take five to seven years. It's a very long process," Dr. Scott Halperin told CTV News Channel on Sunday.

Halperin is the director of the Canadian Center for Vaccinology at Dalhousie University in Halifax, which has been approved to begin trials of the vaccine candidate known as Ad5-nCoV.

He said that due to the nature of the COVID-19 pandemic, his team will carry out tests "in a more accelerated fashion, without sacrificing any safety," by not waiting for full results from one stage of their research before moving on to the next.

"What we want to do is find a vaccine that's well-tolerated by individuals, and that has a good immune response – and then make sure that it works," he said.

Like most clinical trials, this one will be carried out in three phases.

In the first phase, which Halperin said will require up to 100 volunteer participants, the researchers' focus will be less about how the vaccine candidate fights the virus than how humans respond to it in general.

"Volunteers will receive a dose of the vaccine, and they'll be monitored very closely to see the safety of the vaccine, how well it's tolerated and whether it generates a good immune response to the vaccine," Halperin said.

The volunteers, who in this phase will all be between the ages of 18 and 55, will be given a dose of the vaccine and regular blood tests to track their progress over a six-month period. They will also have to keep track of and record any symptoms they may exhibit.

If preliminary data suggests the potential vaccine is safe for humans, the test will move into its second phase, for which hundreds more volunteers of all ages will be needed, without waiting for the full six-month testing period to finish.

These volunteers will still be watched closely for any signs that the vaccine candidate may not be as safe as believed – but there will also be more attention paid to exactly how the body responds to it, such as whether it generates an antibody.

The third and final phase will be the largest of all, requiring thousands of volunteers. It will aim squarely at the biggest question of all: Does the vaccine candidate prevent COVID-19 infection?

"The vaccine is given, and then we wait to see whether people who, when they come in contact with the virus under natural conditions, whether they're protected compared to somebody who just received a placebo immunization," Halperin said.

The Dalhousie team won't only be relying on their own results as they investigate the potential vaccine. Ad5-nCoV was developed in China, where human trials have already entered the second phase. CanSino Biologics, the Chinese company behind the vaccine candidate, has been working with the Canadian government to bring the Canadian trial to fruition.

Jason Kindrachuk, an expert in emerging viruses at the University of Manitoba in Winnipeg, described Saturday's announcement as "amazingly exciting news," especially as it is still unknown what toll the novel coronavirus may take on the human body over the long-term.

"We are still in such a big learning phase right now," he told CTV News Channel on Saturday.

"If we get to a point where we find out that protection doesn't last for years … the vaccine is what we're going to rely on to defeat this virus."

With files from The Canadian Press