Volunteers flock to be vaccine test subjects
Halifax lab leads clinical trial in race for cure
A scant few hours after Prime Minister Justin Trudeau announced Canada’s first clinical trials for a candidate coronavirus vaccine, a barrage of unsolicited emails flooded the Canadian Centre for Vaccinology (CCfV) at Dalhousie University in Halifax.
They weren’t from epidemiologists or doctors. They were Canadians from all over the country volunteering, wanting to be part of the process to provide a first glimmer of hope for a vaccine.
“We never have trouble getting volunteers for our studies, but they’re not usually pounding at our doors,” said CCfV director Dr. Scott Halperin.
He’s been working with CanSino Biologics Inc., based in Tianjin, China, which developed the candidate vaccine. That company has already completed a first phase of clinical trials in China, and has moved on to the next.
With data collected from the Chinese trials, Halperin will have something of a head start on the Canadian trials.
Typically, clinical trials start with a Phase 1, where a small group of subjects between 18 and 55, rigidly screened for their health, will participate in a closely monitored study, primarily to determine if the vaccine has any ill effects on the subjects.
With the head start from the Chinese trials, CCfV will be able to incorporate elder subjects, again rigidly screened for health, into a Phase 1-2 clinical trial. Those trials could begin in a few weeks, pending ethics board approval.
That flood of volunteers for these trials comes as no surprise to Halperin.
In 2014, when the same facility conducted clinical trials for an Ebola vaccine, they had more volunteers waiting in line than they had spots for.
“We actually did a study of our volunteers in Phase1studies for the Ebola study and an influenza Phase1study to find out what was their primary motivation, and the primary motivation was altruism,” he said.
Because of the intensive monitoring that takes place during a Phase 1 study, only those volunteers in the Halifax area will be accepted as test subjects, said Halperin. But he foresees no problem in finding enough local volunteers. “People want to help, they want to be part of the solution. It’s quite amazing. You hear a lot about antivaccination sentiment, but you don’t get nearly as much information about a very dedicated provaccination sentiment and wanting to be part of that solution.”
The vaccine being tested by CCfV works on the basis of preventing the coronavirus from entering the body’s cells. If a virus is unable to enter a cell, it cannot use the cell’s structures to replicate, effectively shutting down the possibility of widespread infection.
Coronavirus has a “spike protein,” which is instrumental in getting the virus through the cell membrane.
The vaccine candidate works by prodding the body to produce antibodies to that spike protein.
For that to happen, researchers use a strain of the adenovirus type 5 virus that’s been modified to be unable to replicate.
Adenoviruses are viruses that generally have a very mild effect on humans, and they can be manipulated to induce immune responses. This makes them useful in serving as a vaccine carrier.
In this case, the virus has also been modified to produce the same spike protein that the coronavirus possesses.
When the body’s immune system sees this virus, it treats it as an external threat and creates an immune response to it. That immune response is directed, in part, toward the spike protein. The next time the body comes across that spike protein — this time perhaps attached to a novel coronavirus — it recognizes that it has already prepared an immune response to it.
Because the immune system has already prepared a response, it is able to rapidly produce the antibody protection that will neutralize the coronavirus. So, rather than the immune response taking a couple of weeks, it takes a day or two.
Once the body has prepared an immune response to an invader, that response is remembered by the immune system. The question of how long the immune system remembers that response — for measles, for example, it’s a lifetime — is one of the details researchers will have to investigate as data comes in from trials and eventually vaccines.
Ironically, the East Coast may not be the best place to test a coronavirus vaccine, though.
Of the four Atlantic provinces, Nova Scotia still has the highest number of active cases — 78 active cases as of Thursday — with only one or two new cases being reported each day. But it still qualifies as a bit of a wilderness for the coronavirus compared to other places in the country.
And that creates problems in testing a candidate vaccine. Once volunteers have been treated with the vaccine, testing for efficacy — how well it works at protecting subjects from the coronavirus — is dependent on subjects coming into contact with the virus at some point.
“You couldn’t do an efficacy study, if there’s only one new case a day, it’d take forever,” said Halperin. “So you really do need to go where the action is, where public health measures are not being implemented or not effective or where there’s an outbreak going on.”
For that next stage of the study, trials will be expanded to other labs in the Canadian Immunization Network (CIRN), a network of 10 clinical trial centres spread across the country, giving the candidate vaccine better exposure to the virus.
Phase 3 of the clinical trials would involve hundreds of subjects, likely in multiple countries, to determine how the vaccine would protect against the virus in near-to-real-world conditions.
Should Health Canada approve the vaccine after that spate of clinical trials, the National Research Council, which has partnered with CanSino, and supplied the cell line that CanSino used to create its vaccine, is preparing itself to manufacture the eventual vaccine in Canada “for emergency pandemic use.”
“You really do need to go where the action is, where public health measures are not being implemented or not effective or where there’s an outbreak going on.”
DR. SCOTT HALPERIN DIRECTOR, CANADIAN CENTRE FOR VACCINOLOGY