Canada’s Ebola vaccine in Guinea
Excerpted from the Ottawa Citizen:
The World Health Organisation is running phase III clinical trials for Ebola virus disease vaccine in Guinea. The technique being used is “ring vaccination” which was used in the 1970s to eradicate smallpox. Co-ordinated by the World Health Organization, the vaccine trial employed the same ring vaccination strategy that was used to eradicate smallpox in the 1970s. Contacts were vaccinated in a “ring” around an infected person, and then their contacts were also vaccinated.
Two groups were vaccinated with the Canadian-developed VSV-EBOV vaccine. The first group received the vaccine as soon as exposure to Ebola was determined. The control group was vaccinated 21 days after exposure. The trials were supported by the governments of Norway and Canada, including Public Health Agency of Canada, Global Affairs Canada, International Development Research Centre and the Canadian Institutes of Health Research.
Other vaccine trials, using other strategies, were conducted, including with a second promising vaccine, in the two other West African countries hit by Ebola. The Canadian-developed vaccine was also tested in Sierra Leone.
The Guinean trial, called Ebola ça suffit (Ebola, that’s enough), was the first of its magnitude to be undertaken in the former French colony during an epidemic. It was a point of pride for many Guineans.
After just four months, in July 2015, interim results of the trial were published in The Lancet. They showed a single dose of the vaccine was up to 100 per cent effective in protecting against Ebola after 10 days. The results made global headlines and the WHO declared the world was “on the verge of a highly effective Ebola vaccine.”
Stephen McGurk, acting president at the International Development Research Centre and a vice-president, programs and partnership, a key Canadian participant in the Guinea vaccine trials, calls the results extraordinary. “Having a successful trial in a critical disease is extremely rare. Under emergency conditions to have a trial as successful as this one — with 100 per cent efficacy — is once in a lifetime. The significance of this vaccine cannot be overstated.”
How did scientists in the centre of Canada, a country that has never had a single case of Ebola, help wrestle the deadly disease to the ground? It began in 1999, when Dr. Heinz Feldmann was hired by the Public Health Agency of Canada to build a high-containment reference centre for the Public Health Agency of Canada — one that could handle the kind of testing that required a Level 4 lab. Feldmann also planned to study Ebola, Marburg and other neglected diseases. Developing a vaccine was not on his radar.
He brought with him a number of systems with which to do research. One used a live animal virus — vesicular stomatitis virus — that causes blister-like sores in the mouth and on the feet of animals, but has little to no effect on humans.
In nature, viruses latch on to cells and inject their genetic material into them. Scientists have figured out how to take advantage of this by taking a virus such as VSV and inserting portions of other genetic material in them. The carrier virus then carries that foreign material to the cells. In this case, the VSV glycoprotein was replaced with that of the Zaire strain of the Ebola virus — the one that ravaged West Africa. The genetically engineered virus could then be used to study the function of the Ebola virus glycoprotein as well as trigger an immune response in a body as if that body had contracted Ebola.
Feldmann said genetically modified VSV offered a means to study the role of the Ebola glycoprotein during infection without the special security otherwise needed to work with the live Ebola virus. His team was interested in studying just how Ebola’s surface protein — which helps a virus attach to a host cell — works, and as well as to determine its toxicity. During that research, something unexpected happened.
The scientists exposed mice to the genetically modified VSV to observe the effect of the Ebola glycoprotein on them. But, rather than becoming sick, the mice remained healthy. The team began wondering whether exposing them to the Ebola glycoprotein in a VSV vector had in fact primed their immune systems against Ebola.
The team got permission to conduct a “challenge” experiment on the mice, to see if they were protected against live Ebola virus infection. They soon had their answer: The mice remained healthy. They were protected’ Canada’s Ebola vaccine was born.
However, before the West African Ebola epidemic became a global health emergency, there was limited interest in Ebola research. The vaccine, which was patented by the Public Health Agency of Canada and licensed to the small U.S. pharmaceutical company in 2010, was sitting on a shelf when the Ebola outbreak began in West Africa.
Despite criticisms that the federal government’s failure to push development of the vaccine more quickly cost lives in West Africa, those who worked on the VSV-EBOV note that vaccine development normally takes decades and that this was developed in a fraction of that time: about 12 months from initial testing on humans to demonstrating its safety and efficacy in what has been called a race against time.
Feldmann said he also would have liked funding for clinical trials sooner, but defends the federal government’s action on the vaccine. “At the time of (vaccine) development happened, we had other public health issues. You could not have justified putting millions or billions into Ebola research at the time with all the other public health problems — chronic disease in particular — that you have to deal with in a developed country.”
Initial clinical trials of VSV-EBOV began in late 2014. In Halifax, one site of the Phase 1 trial to test its safety on humans, researchers were overwhelmed with volunteers, many of whom said they wanted to do what they could to help fight the epidemic after seeing news reports about the crisis in West Africa.
Even with the results of the 2015 vaccine trials in Guinea, there is more research to be done before the vaccine’s manufacturer, Merck & Co., applies for a licence, expected in late 2017. GAVI, the vaccine alliance founded by the Bill and Melinda Gates Foundation, has already signed a deal to buy 300,000 doses of the vaccine to stockpile against future outbreaks, once that licence has been obtained.
Last month, the vaccine was granted “breakthrough therapy designation” by the U.S. Food and Drug Administration and priority status with the European Medicines Agency, which should accelerate its development. Meanwhile, the still-unlicensed vaccine is available on a compassionate basis to help keep any future outbreaks in check. It was used that way earlier this year when Ebola resurfaced in Guinea after the country was initially declared Ebola free last December.
The Ebola vaccine is now being celebrated as “a Canadian success story,” in the words of Alain Beaudet, head of the Canadian Institutes of Health Research. “The Canadian-made Ebola vaccine was a significant achievement,” he wrote. “Our country moved as fast as possible, while maintaining the integrity of the scientific process, and co-ordinating our efforts with international partners. Most importantly, Canada’s vaccine has proven itself to be effective, and holds the promise of saving many lives in the future.”
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The above is excerpted from a more in-depth article, which you can read on The Ottawa Citizen website.