By Kemo Cham
[First published on www.politicosl.com] An Ebola vaccine candidate trialed
in Guinea, Liberia and Sierra Leone has been found to provide 100 percent
protection, raising hopes for a potential prevention of the deadly hemorrhagic
fever disease, the World Health Organisation (WHO) announced Friday.
The breakthrough comes nearly
a year after the end of the world’s deadliest Ebola outbreak that wreaked havoc in West Africa between
2014 and 2016. Over 11,300 people died, out of more than 28,000
cases globally, according to figures from
WHO.
Sierra Leone, Liberia and
Guinea, where it all started, bore the brunt of the cases and fatalities.
About half a
dozen candidate vaccines were put on trial in response to the epidemic. rVSV
EBOV, which is a Canadian made vaccine, was considered as one
of the most promising experimental vaccines among the lot. It was trialed in
all three Mano River Union countries.
It is a vector vaccine, meaning that a
small piece of Ebola virus that cannot cause Ebola is inserted into a different
virus that’s harmless.
A team of
three dozen researchers, headed by Marie-Paule Kieny, WHO's assistant
director-general, found that a 90-percent likelihood during a full-fledged
epidemic that the vaccine would work in more than 80 percent of cases.
Initially developed by Canadian public health
authorities, it was later acquired by the US pharmaceutical giant Merck.
The Guinea trial
was the only one that involved the participation of Ebola cases, meaning it’s
the only one designed to demonstrate the effect of the vaccine on Ebola. Some 11,
000 people were involved in the trial. The vaccine was given to people who had
come in contact with confirmed Ebola patients.
Of the 5,837
people given the rVSV-ZEBOV vaccine, none had a recorded case of Ebola after 10
days or longer, the study reveals.
From another
set of people who were not immediately given the vaccine, called the control
group, 23 cases of Ebola were recorded.
This
is described as the ‘ring strategy’. The
idea is that by vaccinating all people who have come into contact with an
infected person, a protective 'ring' is created so that the virus is stopped
from spreading further.
This,
experts say, was crucial because the West African epidemic was the first ever
experienced in an urban setting.
WHO led the
trial in collaboration with the Ministry of Health in Guinea.
A Guinean
health official praised the breakthrough.
"Ebola
left a devastating legacy in our country. We are proud that we have been able
to contribute to developing a vaccine that will prevent other nations from
enduring what we endured," said Dr. KeÏta Sakoba, Director of National Agency
for health security in Guinea.
As expected,
there were some reports of side effects among those who took the vaccine. While
some reported headaches, fatigue and muscle pain, two patients reportedly had
serious reactions, including one who had an allergic reaction.
This breakthrough also comes after 40
years since Ebola was first discovered. The virus was first identified in 1976
in the former Zaire, now called the Democratic Republic of Congo.
Since then there had been sporadic
outbreaks with little fatalities, until the 2014 West African epidemic.
The UK firm Glaxosmithkline and the
US-based Johnson & Johnson each has a candidate vaccine on trial for Ebola,
as are China and Russia.
A standard approval process for a
new drug or vaccine usually takes at least a decade.
Officials of the pharmaceutical firm
behind the candidate vaccine say it is expected to be available for use in 2018,
if all modalities are put in place as part of a fast-track approval process
planned to be initiated next year.
But a few questions still remains
unanswered about the vaccine. These are its safety on 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 the
vaccine’s effect lasts. The findings only show that the vaccine provides protection
very early after vaccination, and the effect only last after six months.
Hopefully,
answers to these may be obtained from the trials in Sierra Leone and Liberia.
An official
involved with the Sierra Leone trial told Politico recently that a key result
that is pending and which was expected to be available in early next year could
provide answers for immune response to the vaccine and the duration of the
protection that might be given by it.
The Sierra
Leone trial was funded by the United States government through its Centers for Diseases
Control (CDC) which also provided technical assistance to the College of
Medicine and Allied Health Sciences of the University of Sierra Leone as lead
researchers.
Conducted under the Sierra Leone
Trial to Introduce Vaccine against Ebola [STRIVE], it was funded by the US
government through the Centers for Diseases Control (CDC), with expertise from
the USL and the MOHS. More than 8, 000 volunteers vaccinated.
In Liberia
the vaccine was trialed under the Partnership for Research in Ebola Virus in
Liberia [PREVAIL], a joint US-Liberia initiative.
“All of the
studies used slightly different scientific approaches but all were attempting
to show an effect on the disease and to gather information on safety…The
different studies ultimately will provide different information on the vaccine
that can be used to support the application for licensing,” Dr Barbara Mahon, the CDC’s Lead in STRIVE,
told Politico in an earlier interview.
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