Interim results from the Guinean
phase III trial of the Ebola vaccine known as VSV-EBOV, co-funded
by the Wellcome Trust, indicate that it is highly effective against
the virus.
The vaccine shows up to 100 per
cent efficacy in individuals, but more conclusive evidence is
needed on its capacity to protect populations through what is
called 'herd immunity' and the ability to interrupt
transmission.
The Guinea vaccination trial began
in affected communities on 23 March 2015 to evaluate the efficacy,
effectiveness and safety of a single dose of the vaccine VSV-EBOV
by using a 'ring' vaccination strategy. By vaccinating all people
who have come into contact with an infected person you can create a
protective 'ring' and stop the virus from spreading
further.
So far, more than 7,600 people who
have had close contact with Ebola patients, including family
members, neighbours, and co-workers, have voluntarily participated
in the trial.
An independent body of
international experts - the Data and Safety Monitoring Board - have
advised that the trial should continue. The Guinean national
regulatory authority and ethics review committee have also approved
continuation of the trial.
The Wellcome Trust, with
contributions from the UK Department for International Development,
have given more than £5.2 million to support clinical trials of the
VSV-EBOV vaccine. The trial is being implemented by the Guinean
authorities, WHO, Médecins sans Frontières (MSF) and the Norwegian
Institute of Public Health, with support from a broad partnership
of international and national organizations.
Dr Jeremy Farrar, Director of the
Wellcome Trust, said: "This trial dared to use a highly innovative
and pragmatic design, which allowed the team in Guinea to assess
this vaccine in the middle of an epidemic. It is a remarkable
result, and one that shows the power of equitable international
partnerships and flexibility.
"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 VSV-EBOV trial stopped
randomisation on 26 July to allow for all people at risk to receive
the vaccine immediately, and to minimize the time necessary to
gather more conclusive evidence needed for eventual licensure of
the product. Until now, 50 per cent of the rings were
vaccinated three weeks after the identification of an infected
patient to provide a term of comparison with rings that were
vaccinated immediately. This now stops. In addition,
the trial will now include children on the basis of new evidence of
the vaccine's safety.
WHO Assistant Director-General
Marie-Paule Kieny, who leads the Ebola Research and Development
effort, said: "This record-breaking work marks a turning point in
the history of health R&D. We now know that the urgency of
saving lives can accelerate R&D. We will harness this
positive experience to develop a global R&D preparedness
framework so that if another major disease outbreak ever happens
again, for any disease, the world can act quickly and efficiently
to develop and use medical tools and prevent a large-scale
tragedy."
Dr. Sakoba Keita, Guinea's national
coordinator for the Ebola response, said: "This is Guinea's gift to
West Africa and the world. The thousands of volunteers from Conakry
and other areas of Lower Guinea, but also the many Guinean doctors,
data managers and community mobilisers have contributed to finding
a line of defence against a terrible disease."
Dr Dan O'Connor, Head of Humanities
and Social Science at the Wellcome Trust said: "The success of the
'ring' strategy is a hugely important step forward for research
ethics. It shows not only that we can conduct urgently needed,
rapid response research during epidemics, but that we can do so in
a way that is both ethically sound and responsive to the needs of
affected communities."
The paper, Efficacy and effectiveness of an rVSV-vectored vaccine expressing
Ebola surface glycoprotein: interim results from the Guinea ring
vaccination cluster-randomised trial, is published inThe Lancet.