A 27,000-person trial of an Ebola vaccine tested by a London university has started in West Africa. The number of volunteers involved in the trial just tops the number of people that have been infected with the vicious disease since the outbreak began — a harrowing 25,178.
St George’s, University of London, is part of a global effort to quickly bring Ebola vaccine rVSV-ZEBOV to the regions most impacted by the deadly virus, and this week a paper published in the New England Journal of Medicine has shown just how much promise that vaccine has.
In the trial, 158 healthy volunteers in Switzerland, Gabon, Kenya and Germany were given different doses of the vaccine, or a placebo. There were no serious side-effects, though 35 percent reported having a fever and 22 percent experienced arthritis in one to four joints and pain that lasted eight days.
The larger 27,000-person trial, codenamed Prevail, began several weeks ago. That move is a testament to the speed with which Ebola research is now finally moving — too late for many, but still excellent progress. Professor Sanjeev Krishna of the Institute for Infection and Immunity St George’s, who is part an international consortium known as VEBCON that began discussing clinical trial strategies with the World Health Organisation (WHO) back in September 2014, told WIRED.co.uk: “data from the trial regarding safety, and how it’s working, was made available as soon as we had it — even before it hit the public domain.” Prevail was then partly designed using that data.
Another vaccine, cAd3-EBOZ, is also being trialled as part of Prevail. It uses a chimpanzee-derived cold virus to deliver genetic material from the Ebola virus and was partly developed by UK pharmaceutical GlaxoSmithKline. It is, however, a non-replicating vaccine, which could mean larger or repeated doses are needed to ensure immunity. Krishna explains: “the virus is not multiplying in the blood so we need much more of it to generate an immune response.” rVSV-ZEBOV, on the other hand, is a replicating vaccine, which could mean one injection is all that is needed for immunity.
The vaccine uses VSV, a virus that infects cows, horses, pigs and insects, to deliver genetic material from Ebola — in this case, one protein from the Zaire strain that has been prevalent in West Africa in the past year. VSV is relatively harmless to humans, so as it multiplies it should not cause any undue symptoms aside from what has already been shown in the preliminary trial. In making the vaccine, part of the VSV virus is extracted and the Ebola protein inserted, so that as the former replicates, the body builds an immune response to the protein as well.
“Working in areas where there is an outbreak of a virus like this doesn’t give you much opportunity to go back and vaccinate people a second time round,” Krishna tells WIRED.co.uk. “Ideally you’d like to get one shot and know you have protection after a reasonable period of time.”
So far in trials researchers have seen a good immune response, with antibodies to Ebola appearing in volunteers’ blood. But the 27,000-person trial, split between the two vaccines and a placebo, should reveal a clearer picture of what doses work efficiently enough.
St George’s helped the consortium by testing blood samples from volunteers who had received the vaccine. The university was tasked with monitoring how it circulated in the system, and whether or not the vaccine was getting into the saliva or urine. It was not detected in either, a good sign. Working in conjunction with medical facilities in Gabon — with which St George’s already had a two-decade history of collaboration — a sampling schedule was setup so that blood was taken on the first, second and third day of the vaccine being administered, as well as the day before it was administered to establish a baseline. The first few days are when the most side effects are expected — generally flu-like symptoms, as the 158-person trial found — and after seven days all should be relatively clear.
Krishna has been in the unique position of seeing the research pushed through from the initial WHO meeting between VEBCON collaborators in September. At that point, he says, the international teams were only just putting together the framework for how huge collaborative studies could be implemented. “That meeting started on 3 September,” he tells WIRED.co.uk. “Before then, it was just a blank sheet of paper, and we had to do everything within a few months.” The group designed the trial studies, and followed through using West African agencies that had the experience to work on clinical studies in a collaborative and quick manner, while ensuring communication continued effectively, testing was safe, records were kept and the right approvals put in place.
“It was extremely challenging, but also very, very, exciting to think we had the chance to work on something that could be turned around very quickly and might make a difference.”
Krishna believes, however, that next time things will be different. Because there will be a next time one day, whether it’s a flu pandemic or a virus of another form.
“We’re going to have to change things,” he says. “Things were so slow to start with, and there wasn’t a proper response system setup globally to deal with this kind of issue. Now there are all sorts of people looking at this at different levels, and it has to be looked at urgently. We have to have a system that will readily be able to cope not just with Ebola, but Sars or a flu pandemic.”
“We’ve just got to do better.”