Breakthrough in the search for an Ebola Vaccine
The publication of positive results from the Ebola VSV-ZEBOV vaccine trial is being met with excitement. Charlie Weller oversees the Wellcome Trust’s Ebola funding and explains why the news is such a big achievement.
Today's publication of research showing the efficacy of the Ebola VSV-ZEBOV vaccine represents an incredible and humbling achievement that has only been possible due to the global collaboration of researchers, NGOs, governments, industry and funders – all working towards a unified goal.
The results of this interim report include data from approximately 7,500 people given the vaccine and suggest that a single injection of VSV-ZEBOV might be highly effective in preventing people from contracting Ebola. An effective vaccine against Ebola could reduce deaths and end this devastating epidemic that has had a huge social and economic impact.
Think back to summer last year. The Ebola epidemic was in the news daily, spreading to new countries, and the number of people dying due to the outbreak was rapidly increasing.
It was a very serious situation, with no vaccines known to protect against Ebola, or drugs to treat those people who were infected.
Developing vaccines from scratch takes years. Promising Ebola vaccine candidates existed, but only one had been tested in humans and was subsequently abandoned. There were no Ebola vaccines ready to be tested in West Africa to see if they could protect people from contracting the virus.
It normally takes over two years to determine whether a vaccine is safe for use in humans and whether it can offer protection against a disease. The growing scale of the outbreak meant this process needed to be accelerated if there were to be any hope of developing a vaccine in time to impact the current epidemic.
The global community faced an enormous challenge – and time was not on our side.
In response to this the Wellcome Trust created an Ebola research fund and invited applications from researchers doing clinical trials to test vaccines and drugs that could impact the current epidemic. The first applications arrived within days of our funding announcement in August 2014.
Usually the funding cycle from application to award takes around eight months, but thanks to the good nature and hard work of many people – including reviewers, applicants and Wellcome Trust staff – who took on Ebola work on top of their usual duties, we were able to speed up the process considerably.
One of the applications we received was a proposal to assess the safety of the Ebola vaccine VSV-ZEBOV, developed originally by the Health Agency of Canada. This was one of the projects that received fast-tracked funding through the Ebola research call.
By the start of October it was funded and by the end of the month the first healthy volunteers were being vaccinated to assess safety of the vaccine. The trial sites were in Europe (Germany and Switzerland) and Africa (Gabon and Kenya). In parallel we co-funded (with the MRC and Department for International Development) the safety trial of another promising Ebola vaccine, ChAd3, led by Professor Adrian Hill at the University of Oxford.
As the epidemic progressed, and following positive results of the safety trial, a second proposal was received in December to assess whether the VSV-ZEBOV could protect people from Ebola. The researchers planned to use an innovative trial design where the family, friends and contacts in a 'ring' around a patient who had contracted Ebola would be given the vaccine.
Funding was agreed and, in March 2015, the first Ebola-infected individuals were identified and the ring vaccination began in Guinea, which continues to have the majority of Ebola positive cases.
Vaccination was given immediately or delayed by three weeks to assess the ability of the VSV-EBOV vaccine to protect against the disease. The results showed it to be so effective that as of 26 July, all trial participants are being given the vaccine immediately. The trial partners, including the Guinean authorities, WHO, Médecins Sans Frontières (MSF) and the Norwegian Institute of Public Health are now working to minimise the time taken to gather essential data that could lead to the vaccine being licensed.
The results published today are positive for two reasons. Not only does this vaccine candidate appear to give effective protection against the Zaire strain of Ebola, but we’ve got to this point in approximately eight months, rather than years.
We're not out of the woods yet though. It’s critical that people in the affected countries continue to be given the vaccine as part of a clinical trial, to allow the research team to gather enough evidence to get the vaccine licensed.
While the community undoubtedly deserves credit for enabling this work to be fast-tracked, we should also stop to think what could have been achieved if the VSV-ZEBOV vaccine had been assessed for safety straight after the initial preclinical work.
If the safety testing work had been done earlier – before the urgency of the outbreak – the vaccine's efficacy could have been assessed much sooner, perhaps changing the course of the epidemic and ultimately saving lives.
This transition from preclinical to safety clinical trials is a sticking point in the vaccine development pathway that is not unique to Ebola vaccines, but for many other infectious diseases. The global community has not previously been willing or able to invest in the complex and costly development process required to develop new vaccines.
If we want to reduce the risk of being caught out by future epidemics, we need to address this problem. Writing in the New England Journal of Medicine recently, Wellcome director Jeremy Farrar outlined a proposal to establish a global development fund to accelerate discovery and development of new vaccines.
Commenting on today's news, Jeremy said: "Our hope is that this vaccine will now help bring this epidemic to an end and be available for the inevitable future Ebola epidemics. This partnership also shows that such critical work is possible in the midst of a terrible epidemic. It should change how the world responds to emerging infectious disease threats. We, and all our partners, remain fully committed to giving the world a safe and effective vaccine."
The community has already shown the power of working together during a crisis, continuing to do so could be key to improving our future epidemic preparedness.