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 In an effort to save lives, health authorities are determined to
roll out potential vaccines within months, dispensing with some of
the usual testing, and raising unprecedented ethical and practical
questions.
"Nobody knows yet how we will do it. There are lots of tough
real-world deployment issues and nobody has the full answers yet,"
said Adrian Hill, who is conducting safety trials on healthy
volunteers of an experimental Ebola shot developed by
GlaxoSmithKline.
Hill, a professor and director at the Jenner Institute at Britain's
University of Oxford, says that if his results show no adverse
side-effects, GSK's new shot could used in people in West Africa by
the end of this year.
Even if a drug is shown to be safe, it takes longer to prove it is
effective - time that is simply not available when cases of Ebola
infection are doubling every few weeks and projected by the World
Health Organization to reach 20,000 by November.
Among questions that scientists are grappling with: should an
unproven vaccine be given to everybody, or just a few? Should it be
offered to healthcare workers first? The young before the old?
Should it be used first in Liberia where Ebola is spreading fastest,
or Guinea where it is closer to being under control?
Should people be told to assume it will protect them from Ebola? Or
should they take all the protective measures they would if they
hadn't been vaccinated? And if so, how will anyone know whether the
vaccine works?
GSK is one of several drug firms that have either started or
announced plans for human trials of candidate Ebola vaccines. Others
include Johnson & Johnson, NewLink, Inovio Pharmaceuticals and
Profectus Biosciences.
The WHO says it hopes to see small-scale use of the first
experimental Ebola vaccines in the West Africa outbreak by January
next year.
It has convened vaccine specialists, epidemiologists, pharmaceutical
companies and ethicists, for a meeting on Monday and Tuesday to
discuss the moral and practical issues.
"Normally safety is the absolutely paramount thing when you're
developing a new vaccine, but this time we're going to have to take
more risks," said Brian Greenwood, a professor at the London School
of Hygiene and Tropical Medicine who will take part in the WHO-led
meeting.
"Quite how we do that, and what risks we take, hasn't really been
thought through yet. That's what people are trying to figure out."
TWO THINGS AT THE SAME TIME
The chaos caused by the epidemic itself makes it even more difficult
to deploy and track use of a new vaccine, said Hill.
"You're trying to do two things at the same time: you're trying to
evaluate a vaccine and deploy it - when normally you would evaluate
the vaccine first, by doing a randomized double blind controlled
trial, and then you'd deploy it if it was shown to be safe and
effective."
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Because Ebola virus is so deadly, those who receive a trial vaccine
must be told to take all other precautions and protect themselves
fully. This could make it harder for researchers to decipher whether
the protective clothing and safety protocols, or the new vaccine, is
what kept them safe.
Normally researchers testing a vaccine would give some volunteers a
placebo, or dummy, to create a "control" group to compare against
those who get the real drug. That seems unthinkable in a situation
where disease with a death rate of up to 90 percent is raging
through villages.
"Would it be ethical to do a trial where some people don't get the
vaccine because they are in the control group? Most people think it
wouldn't be - especially if you have reasonable evidence that the
vaccine might work," said Hill.
Jeremy Farrar, an infectious diseases expert and director of the
Wellcome Trust medical charity, said limited supplies of any
candidate vaccine could result in a form of natural control group
being formed anyway. Researchers can compare populations where the
vaccine is available with those where it isn't.
GSK has said it is aiming to have 10,000 doses of its experimental
shot by the end of the year, while Canada has given 800 vials of the
NewLink candidate vaccine to the WHO, expected to yield at least
1,500 doses.
Most experts interviewed by Reuters favor the idea of the first
doses going to frontline healthcare workers, since their exposure to
risk is so high. Researchers could then compare infection rates
among health workers who receive the vaccine to those working in
regions still waiting for it.
Peter Piot, a co-discoverer of the Ebola virus in 1976 and now
director of the London School of Hygiene and Tropical Medicine said
that however complicated the ethics, reverting to the traditional
years-long process of testing vaccines, and withholding them from
West Africa until then, is not an option.
"It may be that without a vaccine, we can't really stop this
epidemic," he said.
(Reporting by Kate Kelland; Editing by Peter Graff)
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