Experts will be
meeting this week
at the World Health Organization (WHO) to discuss the role of new drugs
and vaccines to help control the Ebola epidemic in West Africa. Last
month, the WHO said that it is
ethical
to provide experimental drugs and vaccines for Ebola, but that there’s
also a “moral duty” to conduct clinical trials of these experimental
drugs and vaccines to determine whether they’re safe and effective. At
the same time, a
new study
released last week shows that the Ebola virus is mutating rapidly,
which could make it more transmissible or reduce the effectiveness of
drugs and vaccines in the pipeline.
ZMapp
is the drug that’s gotten the most attention so far. It’s a combination
of three antibodies, proteins that bind and neutralize the Ebola virus.
ZMapp has been administered to seven Ebola patients, and the
manufacturer says its supplies have been exhausted. It is too early to
know whether
Will Pooley—the
British nurse who contracted Ebola while caring for patients in Sierra
Leone—will survive the disease. Two of the other six ZMapp recipients
have died. Those who survived may have done so because they received
good supportive treatment, because they were younger and didn’t have
other medical problems, or by random chance (which is more likely to
happen when you’re dealing with such small numbers). While ZMapp
cured 18 primates infected with Ebola virus, there’s still much we don’t know. ZMapp still hasn’t yet been studied in humans.
Other candidate treatments for Ebola include
TKM-Ebola,
AVI-7537,
favipiravir,
selective estrogen receptor modulators like clomiphene and toremifene,
BCX-4430 and
ST-383. In July, the Food and Drug Administration (FDA)
put on hold
a small trial of TKM-Ebola in healthy volunteers because the drug
caused an inflammatory, flu-like response at higher doses—inflammation
is also how Ebola causes disease and kills. TKM-Ebola works by shutting
down the Ebola virus’ genes through a new technology called
RNA interference. The FDA has since
modified that hold to allow patients sick with Ebola to receive TKM-Ebola. Early human studies of AVI-7537 were
stopped due to budget cuts
at the U. S. Department of Defense, which was funding the trials.
Favipiravir is used to treat influenza, and selective estrogen receptor
modulators have been used to treat female infertility and breast cancer,
so we know they are safe to use in humans. And while they show promise
as Ebola drugs, they haven’t yet been studied in Ebola patients.
BCX-4430 and ST-383 have yet to be studied in humans.
Vaccines to prevent Ebola are also being developed. Ebola vaccines
were first tested in humans beginning in 2003. Human safety studies of
an experimental Ebola vaccine developed by the National Institutes of
Health (NIH) and GlaxoSmithKline will
launch this week.
If the vaccine appears safe, GSK plans to donate up to 10,000 doses of
the vaccine to protect those at highest risk. NIH is also working with
Crucell,
Profectus Biosciences,
Immunovaccine and researchers at
Thomas Jefferson University
to develop other candidate vaccines for Ebola. Human trials of the
Crucell vaccine are planned for late 2015 or early 2016. Another
experimental Ebola vaccine, VSV-EBOV, has been developed by the Public
Health Agency of Canada and is licensed to
NewLink Genetics.
Studies of VSV-EBOV among healthy human volunteers will start in
October at the Walter Reed Army Institute for Research. In addition, the
Canadian government is
donating
up to a thousand doses of VSV-EBOV to the WHO, and NewLink Genetics is
trying to ramp up production of its vaccine over the coming months.
Researchers have estimated that
thousands, if not tens of thousands, of doses of a new Ebola drug or vaccine would be needed to help those in need.
It’s important to study and roll out new Ebola drugs and vaccines,
but not at the expense of measures that we know work. We know that
supportive care — to maintain adequate blood pressure, replenish lost
electrolytes and treat complications — can reduce mortality from Ebola,
but access to such care remains limited in West Africa. And while some
of the new drugs may prove effective for treating Ebola patients, it’s
unclear whether they will prevent spread of the virus from
person-to-person. An epidemic can’t be contained if transmission isn’t
blocked. According to Dr. Anthony Fauci, director of the National
Institute of Allergy and Infectious Diseases, “we know the best way to
prevent the spread of Ebola infection is through public health measures,
including good infection control practices, isolation, contact tracing,
quarantine, and provision of personal protective equipment.” He added,
“However, a vaccine will ultimately be an be an important tool in the
prevention effort. The launch of Phase 1 Ebola vaccine studies is the
first step in a long process.”
In the meantime, priority must be given to identifying cases so that they may be given
supportive care
and isolated to prevent further spread, and to trace and test those who
may have been in contact with Ebola victims. Healthcare workers need
adequate supplies of personal protective equipment, and need to know
how to use it
to avoid being infected themselves. But it will be difficult to
accomplish these goals, or to make use of new drugs and vaccines,
without significant investment to strengthen health systems in the
affected countries, above and beyond
WHO’s US$489 million plan
released last week. Meanwhile, many others are dying from malnutrition
due to food scarcity, infections like malaria and typhoid, complications
of childbirth and other conditions that overwhelmed, crumbling health
systems are not treating.
New technologies are appealing, but they aren’t cure-alls, especially
in poor, dysfunctional health systems. To illustrate this, I’ll draw
from our experience with tuberculosis, which kills an estimated 1.3
million people per year globally. The most common test for tuberculosis
dates back to the 1800s. Up until recently, it took up to two months to
make a diagnosis of TB, allowing patients to get sicker and even die.
But then scientists developed a new test, the
GeneXpert,
which could diagnose TB in less than two hours. Many infectious
diseases and public health experts were convinced that using the
GeneXpert would lead to more rapid treatment of patients, thereby saving
lives. Some said that we had an ethical obligation to offer it to
everyone because it was clearly so much better. In 2011, the South
African Department of Health embarked on a real-life experiment of the
GeneXpert. They found that using the new test made no impact on
mortality. It’s not that the GeneXpert didn’t work, it’s that the test is only one small part of the process.
Diseases of the poor receive
too little attention
from medical researchers and pharmaceutical companies. We should be
investing more to develop drugs and vaccines to combat diseases like
Ebola. But we also can’t afford to wait. It’s urgent that we invest in
strengthening health systems to make better use of existing tools, and
eventually, new drugs and vaccines.
PHOTO: Residents of West Point celebrate the lifting of a quarantine by the Liberian government, in Monrovia, August 30, 2014.nijanewspaper.blogspot.com
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