A vaccine
developed by Merck is the first shown to be highly effective in preventing
human infection with Ebola, according to final results from a clinical trial.
Among 5,837
people who received the rVSV-EBOV vaccine in the trial in Guinea in 2015,
no Ebola cases were recorded 10 days or more after vaccination, signalling 100
percent protection.
Caption: The Ebola virus, as seen through a microscope. At its peak, the virus infected as many as 400 people a week in Liberia. PICTURE: Reuters More than
11,300 people died in West Africa's 2013-2016
epidemic of the virus, which causes hemorrhagic fever.
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'When the next Ebola outbreak hits, we will not be defenceless,' said
Marie-Paule Kieny, a World Health Organisation (WHO) assistant director-general
and one of the lead researchers in the trial.
Merck's
rVSV-EBOV has already been used in Sierra Leone to contain a flare-up
there.
The Guinea trial
took place in the coastal region of Basse-Guinée, which was still seeing new
Ebola cases when the trial started in 2015.
It used a ring vaccination approach, in which, when a new Ebola case was diagnosed,
researchers traced all people who might have been in recent contact and logged
them as clusters, or rings, made up of an average of 80 people.
At first,
the clusters were assigned to receive the vaccine either immediately or after a
three-week delay.
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After interim results showed 100 percent protection in those vaccinated immediately,
the trial design was switched to allow all clusters to be given the shot
straight away.
The WHO
said that if Ebola outbreaks occurred before the vaccine was given full
regulatory approval, it could be made available though a compassionate use procedure
after informed consent.
John Edmunds, a professor of infectious disease modelling at the London School
of Hygiene & Tropical Medicine, whose team helped design the trial, hailed
its success as 'historic'.
'When Ebola
strikes again we will be in a much better position to offer help to affected
communities, as well as protect the brave volunteers who help control this
terrible disease,' he said in an emailed statement.
GAVI, the
global vaccine alliance, provided $5 million earlier this year to buy 300,000
doses of rVSV-EBOV as a stockpile for use during future Ebola outbreaks.
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