Canada's first homegrown COVID-19 vaccine has shown high efficacy against infection during Phase 3 clinical trials, the drugmakers behind the plant-based shot reported Tuesday, fuelling hopes it could soon get a stamp of approval for use.
Medicago, a biopharmaceutical company headquartered in Quebec City, and British-American vaccine giant GlaxoSmithKline (GSK) are now gearing up for their final regulatory submission to Health Canada.
The vaccine's overall efficacy rate against all virus variants studied was 71 per cent, with a higher efficacy rate of 75 per cent against COVID-19 infections of any severity from the dominant delta variant, the companies said in a news release.
The results followed a global, Phase 3, placebo-controlled study of the two-dose vaccine that was launched last March. The newly discovered omicron variant — recently confirmed in various countries around the world, including Canada — was not circulating during the trial period.
If licensed in this country, the shot would be the first COVID-19 vaccine using virus-like particle technology and the first plant-based vaccine ever approved for human use, Brian Ward, medical officer for Medicago, said during a recent interview with CBC News.
"This would be a first for the world," he added, "not just for Quebec and Canada."
The shots use Medicago's plant-derived, virus-like particles — which resemble the coronavirus behind COVID-19 but don't contain its genetic material — and also contain an adjuvant from GSK to help boost the immune response.
In the vaccine's Phase 3 trial, no severe cases of COVID-19 were reported in the vaccinated group, the release notes. No related serious adverse events were reported either, and reactions to the shots were "generally mild to moderate and transient," with symptoms lasting, on average, only one to three days.
"I think there will be an important need for our vaccine, both to increase the number of doses available for those who haven't had any vaccines yet, but also possibly for those who need a booster dose," Ward said.
Results are promising, immunologist says
National Advisory Committee on Immunization working group member Matthew Miller, an immunologist at McMaster University in Hamilton who is working on developing a different type of vaccine for COVID-19, said the Medicago trial results are promising on both efficacy and safety.
He noted that the public information was so far limited to a news release, much like previous announcements from other vaccine manufacturers.
The trial itself was also hindered by time constraints and didn't specifically break down the level of protection against severe illness. That's because there were too few serious COVID-19 cases in the placebo arm and none in the vaccine arm, limiting the ability to draw strong conclusions, Miller said.
"Nevertheless, I think we can expect that with 75 per cent protection against any infection, you would expect even stronger protection against severe illness; that's been universally true of every single other vaccine," he added.
"The durability of that response, I think, is still a question that we'd have to wait and see."
WATCH | Canada's first homegrown COVID-19 vaccine shows promising early results:
The Phase 2 portion of the trial at multiple sites in Canada and the United States involved a mix of healthy adults, those with comorbidities and seniors over the age of 65, while the Phase 3 portion expanded to more than 24,000 participants in various countries.
If approved for use, the shot may help jump-start Canada's sluggish vaccine production sector, said Miller, who has no current affiliation with Medicago but previously sat on a panel advising the company on influenza vaccines.
Canada lost its vaccine manufacturing capacity over time, but that could change with several Canadian COVID-19 vaccines currently in development, said Lakshmi Krishnan, director general of human health therapeutics at the National Research Council of Canada.
"We hope that in due time, all of that will align and we will be able to produce vaccines in Canada," she said.
Trial looked at range of variants
Medicago is now one of the first to share trial results on how well its vaccine works against a range of variants, Ward said, unlike those earlier in the pandemic, which focused on the earliest strain of SARS-CoV-2.
The trial showed nearly 89 per cent efficacy against the gamma variant, with no cases of alpha, lambda or mu variants observed in the vaccinated group, while 12 cases were observed in the placebo arm.
While there's concern over the omicron variant and whether it may evade some level of vaccine- or infection-based immunity, Ward said the company plans to get that data for its vaccine as soon as possible.
"The goalposts have moved," Ward said.
Full results of the Phase 3 study will be released in a peer-reviewed publication, Medicago's release noted.
If Health Canada gives the green light to the vaccine, it would be the fifth COVID-19 shot approved for use in Canada, alongside those from Pfizer-BioNTech, Moderna, AstraZeneca and Johnson & Johnson.