By Thomas M. Burton And Peter Loftus
European researchers said an experimental Ebola vaccine tested
in West Africa might be highly effective in protecting people from
the deadly virus, raising the possibility that it could be used to
prevent future epidemics.
The vaccine, from Merck & Co. and NewLink Genetics Corp. and
dubbed VSV-ZEBOV, is one of a handful of vaccines and drugs that
were rushed into bigger studies after a big Ebola outbreak hit West
Africa last year. About 27,780 people have been infected and about
11,290 have died, according to the World Health Organization.
In the trial, conducted in Guinea, 4,123 people who had been
exposed to Ebola were randomly assigned to immediately receive the
vaccination, and 3,528 were assigned to delayed vaccination after
21 days.
The results, published online Friday in the British journal the
Lancet, suggest the vaccine may be highly effective beginning 10
days after inoculation. None of those patients getting the vaccine
immediately got sick after 10 days. By contrast, 16 people got sick
in the control group of people who were randomly assigned to be
vaccinated 21 days after exposure to the virus.
"The hope was a vaccine might be developed in sufficient time to
have an impact to help control and maybe help eliminate this Ebola
outbreak if it were to persist," said Mark Feinberg, Merck's chief
public-health and scientific officer. "The study did provide strong
evidence supporting vaccine efficacy. Whether this evidence by
itself will be seen by all stakeholders as definitive will be an
important discussion."
Behind the scenes, debate over the study's methodology
continues. People familiar with the issue said the U.S. Food and
Drug Administration prepared a critical commentary about the study
for publication in the Lancet. The FDA commentary was described as
saying that the trial didn't meet scientific standards and the
results didn't produce statistically significant results.
However, that journal didn't publish the FDA critique on Friday.
Inquiries made to senior editors there, Richard Horton and Astrid
James, went unanswered.
Also, some U.S. officials said the researchers changed the
protocol during the trial--generally a troublesome step-- by
deciding to measure cases only after a 10-day period. One of the
study's authors, John-Arne Rottingen, said the researchers always
intended to measure cases 10 days after people were randomly
assigned.
The World Health Organization, with funding from groups like
England's Wellcome Trust and France's Doctors Without Borders,
conducted the study in Guinea beginning in April to test whether
the VSV-ZEBOV vaccine could prevent new Ebola infections.
The incidence of new cases has waned this year, raising the
prospect that some clinical trials already under way won't provide
definitive results in humans about whether those experimental
vaccines and therapies are safe and effective.
The Guinea study was designed as a so-called ring-vaccination
trial, in which researchers identified newly diagnosed Ebola cases.
In village A, a ring of people who were in contact with the sick
person were immediately vaccinated. In village B, all such people
were vaccinated but only after 21 days. Village C was immediate,
village D after 21 days, and so on.
The design embodied European researchers' argument that people
shouldn't be randomly assigned to placebo. But U.S. researchers,
with the FDA and National Institutes of Health, contend that only a
"gold-standard" trial with people randomly assigned to get the
vaccine or a placebo could produce the most compelling results.
The Guinea study will continue, but all people in contact with
an infected person will get the vaccine immediately, and no one
will get delayed inoculation.
Seth Berkley, president of the vaccine-dispensing GAVI Alliance,
said this vaccine has been stored at minus-80 degrees Celsius
(minus-112 degrees Fahrenheit), but that stability testing is under
way to see if it can be used much more widely. He said a stockpile
of vaccines for future epidemics is being considered, and that
other experimental vaccines will also be considered.
On Friday, Anthony S. Fauci, director of the NIH's National
Institute of Allergy and Infectious Diseases, called the findings
very impressive. "It's a complex trial design," he said, "but it's
a step forward." He said it is unlikely the NIH's own study of the
Merck vaccine and of another made by the NIH will move ahead in
humans, largely because "there are almost no cases in Guinea"
now.
Write to Thomas M. Burton at tom.burton@wsj.com and Peter Loftus
at peter.loftus@wsj.com
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