Canada's experimental Ebola vaccine: How does it work?
Marlene Leung, CTVNews.ca
Published Wednesday, August 13, 2014 9:56PM EDT
The Public Health Agency of Canada and the federal government have shared more details about an experimental Ebola vaccine that will be donated to help fight the current outbreak in West Africa.
Dr. Gary Kobinger, chief of special pathogens at the agency, and Heritage Minister Shelly Glover shared more information about the VSV-EBOV vaccine at a news conference Wednesday afternoon.
Here's what we know so far about the made-in-Canada vaccine.
How many doses will be sent?
Canada will be donating between 800 to 1,000 doses of the vaccine. A small amount of the vaccine will remain behind, in the event it is needed for "compassionate use" in this country, Federal Health Minister Rona Ambrose said Tuesday in a statement.
The decision to donate the vaccine came hours after the World Health Organization said that it would be ethical to use untested treatments to fight the Ebola outbreak.
The WHO stipulated that countries that offer experimental drugs or vaccines to consenting patients must also collect data for research purposes.
Who owns the vaccine?
The scientists at the National Microbiology Lab who helped develop VSV-EBOV and the federal government own the intellectual property associated with the vaccine. The federal government licensed the rights to further develop the product for human use to BioProtection Systems, a U.S.-based biotechnology company.
How does the vaccine work?
Kobinger said the vaccine can be administered before exposure to the Ebola virus, and in animal models it has also shown efficacy after exposure.
"It can have action on both sides, a little bit like the rabies vaccine," he said.
Kobinger said the scientists who are developing the vaccine do not yet fully understand the vaccine's precise mechanism, but there are a number of hypotheses they are studying.
One hypothesis is that the "extremely potent" vaccine stimulates an immune response to protect the individual against the virus in a sort of "race," he said.
In this model, the individual will be protected if their immune response develops fast enough and before the virus grows.
The second hypothesis being considered is based off of a model in which the vaccine "competes" with the virus for target cells, which replicate the virus.
If we don't fully understand it, is it safe?
Kobinger noted that in the clinical development of any new vaccine the first step is to establish efficacy. Once that has been established, researchers typically work on establishing the vaccine's safety for human use.
The scientists behind VSV-EBOV have been researching its safety for about a year now, he said, noting that efficacy and safety are measured separately.
"Safety is completely different than efficacy," Kobinger said. "The safety and efficacy of a vaccine don't necessarily go together, so you can't judge the safety based on efficacy."
The vaccine has never been tested in humans in the context of safety trials, however there was one individual who received the vaccine after lab exposure to the virus in Germany, he said.
That person did not go on to develop Ebola, and did not experience any known severe adverse events, Kobinger said.
He added that the vaccine has been tested in animals, and researchers have not recorded any serious adverse events from those animal trials.
Who will get the vaccine?
Glover said the WHO will be assembling a panel of experts who will be responsible for deciding how and where to distribute the vaccines.
She said the global health agency will decide which countries to send the vaccine to, and which individuals in those countries will get the vaccine.
Earlier on Wednesday, infectious diseases expert Dr. Neil Rau told CTV News Channel that he believes the best use of this vaccine is to give it to consenting medical staff working on the front lines of the outbreak to see if it protects them against contracting the virus.
Dr. Gregory Taylor, of the PHAC, said the agency had also been advised similarly.
Glover stressed that the decision of where the vaccines end up going will not be politically based.
"This is not a political decision at all," she said at Wednesday's news conference. "This is a very serious disease. This has taken the lives of many, many people, and we're doing our part as a country to provide assistance to the global community.
"This is a decision that will be made by experts and not politicians."
When will the vaccines leave Canada?
Glover said that the vaccines are in Winnipeg, ready to go at "a moment's notice," and can be shipped out once the WHO decides how to distribute them.
Is Canada donating anything else?
In addition to the vaccines, Canada has donated a mobile lab for rapid diagnostic testing, which will be stationed in Sierra Leone.
Kobinger said the ability to perform rapid diagnosis is one of the "proven" tools that will help health officials contain the outbreak.
"The real tools that have been proven (are) to be on the ground, to do rapid diagnostic (testing) and to isolate and to break the train of transmission," he said.
The mobile lab will allow doctors diagnose and treat people who have been infected in the proper environment, he said.
The current Ebola outbreak in West Africa has killed more than 1,000 people and now involves four countries: Guinea, Sierra Leone, Liberia and Nigeria.
The federal government says that to date, it has donated about $5.2 million to address the Ebola outbreak.