A prototype vaccine for
Ebola may be "up to 100 per cent effective" in protecting against the
deadly virus, the World Health Organization (WHO) said Friday.
If all goes well, the vaccine could become available in 2018 under a fast-track approval process, it said.
In a major
clinical trial, nearly 6,000 people in Guinea were given the test
vaccine last year, at the tail end of a lethal epidemic of Ebola.
Not one of the 6,000 contracted the disease.
But in a control
group of volunteers that did not receive the vaccine, 23 Ebola cases
occurred, researchers reported in The Lancet medical journal.
"If we compare
zero to 23, this strongly suggests that the vaccine is very effective,
that it could be up to 100 percent effective," Marie-Paule Kieny, WHO's
assistant director-general and lead author of the study, told AFP.
Her team of three
dozen researchers calculated a 90-percent likelihood during a
full-fledged epidemic that the vaccine, dubbed rVSV-ZEBOV, would work in
more than 80 percent of cases.
"After 40 years,
we appear to now have an effective vaccine for Ebola virus disease to
build upon," Thomas Geisbert, a scientist at Galveston National
Laboratory in Texas who did not take part in the study, wrote in a
commentary, also in The Lancet.
Compassionate
First identified
in 1976 in what is now the Democratic Republic of Congo, the Ebola virus
erupted periodically in outbreaks of up to a couple hundred cases,
mainly across west and east Africa.
In early 2014, however, a handful of infections in southern Guinea mushroomed rapidly into an epidemic.
Over the next two years, more than 28,000 people fell ill, mainly in Guinea, Liberia and Sierra Leone. Some 11,300 died.
With a mortality
rate above 40 percent, the disease — one of a category of so-called
haemorrhagic fevers — has an incubation period of up to three weeks. It
causes violent and painful symptoms, including vomiting, diarrhoea,
organ failure and internal bleeding.
The new vaccine
was initially developed in Canada by public health authorities before
being taken over by pharmaceutical giant Merck.
It is slated to
be submitted by Merck to health authorities in the United States and
Europe sometime next year under a fast-track approval process.
"We may have a
vaccine which is registered in 2018," Kieny told journalists at a press
conference Thursday, noting that the standard approval process for a new
drug takes a decade, if not more.
In the meantime,
Merck has committed to ensuring that 300,000 doses of the vaccine are
available for emergencies under a protocol called "compassionate use".
"They will be able to produce a million in very short period of time," Kieny noted.
Unanswered questions
There are still questions to be resolved concerning the vaccine, including side effects.
Initial tests last year did not include children, while the most recent trials covered those over six years old.
Of the more than
6,000 people injected with the Ebola vaccine only two showed serious
adverse effects, the study reported. Both recovered fully.
But it is still
unknown if the vaccine is safe for children six and under, pregnant
women, or people with the AIDS virus — all groups that were excluded
from the most recent trials.
Another unknown is how long innoculation lasts.
"With the
Canadian Merck vaccine, you have a protection very early after
vaccination, but we don't know if it will last after six months," Kieny
said.
Other Ebola
vaccines under development — some of which have been tested in humans —
could prove more effective over a longer period.
British firm
Glaxosmithkline and Johnson & Johnson, based in the United States,
each have experimental products in the pipeline.
China and Russia
have also developed vaccines, with the Russian one having just finished
the second phase of three-step clinical trials.
No comments :
Post a Comment