A Canadian-made experimental vaccine against Ebola is about to begin human trials and holds our best hope for immunizing those at risk. The big question, however, is whether or not it be ready in time to stop the spread of this deadly disease.
At this point the vaccine, dubbed VSV-EBOV, has proven to be 100% effective in primates, both in preventing sickness and increasing survival rates in infected individuals when given promptly after diagnosis.
At this point the vaccine has not been tested in humans, but experts are quite hopeful.
“As with any infectious disease, whether it’s Ebola or the flu, vaccines have historically been where you get the biggest bang for the buck, in terms of being the most effective means of disease control,” said infectious disease expert Andrew Potter, who is the CEO and Director of the Vaccine and Infectious Disease Organization at University of Saskatchewan.
“We hope it will work just like with the recent pandemic H1N1 flu. The vaccines that were rolled out quickly at the time did a phenomenal job in mitigating the risk of what we were facing.”
With the initial tests using the prototype vaccine via animal model testing having been so successful, Phase 1 Human trials with volunteers are set to begin this week in a lab in Maryland.
Looking forward, with so much at risk from the spread of Ebola, an accelerated testing schedule can be expected, says Potter.
Typically there would be 3 sets of clinical trials to get a vaccine approved which can last as long as 7 months, even when sped up. The main reason: Acute safety is most important, making sure no adverse affects crop up when the vaccine is administered.
Phase One would be a safety trial in a limited number of patients who are healthy adults. Phase Two would be carried out in a larger number of volunteers where again the efficacy would be looked at. Finally Phase Three can be years in length and involve thousands of individuals.
“In this case however there is clearly a degree of urgency to get this out, so from my perspective, they’re going to have to prove it’s safe obviously and make sure that it generates an immune response the same way as it did in the animal models,” Potter said..
Researchers will have a good idea of how well the vaccine is working when they begin to get measurements of the levels of antibodies in the volunteers that are vaccinated. If it works like it’s supposed to, then their immune system would be able to recognize the virus, produce antibodies against Ebola, and essentially neutralize it if they came into contact with it in the future.
Already there is a great body of evidence that is starting to come out that immunity does play a role in the survival of the patient. For example, the latest patient in Texas is being given plasma transfusion from the first American doctor who was infected in Africa and brought back to the U.S. for treatment.
The big question now will be, can we make enough of the vaccine?
“This could be a problem because at this stage in the game it’s just not easy to all of a sudden go from lab scale to full blown production,” added Potter.
While he does believe we are pretty late in getting a vaccine out, there is no doubt it will still have major benefits to the population at risk since a vaccine will not only help prevent the disease but also prevent the spread the virus.
“The strategy that we use for immunization is to essentially take infected areas and surround it with vaccinated individuals, much like a firewall to stop the spread,” he added.
“I really believe it is never too late. We’ve had Ebola outbreaks ever since it was identified in 1976 at routine intervals, so while we may not get the most bang for the buck during this outbreak will will be prepared for the next one.”
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