Government researchers, in collaboration with British drugmaker GlaxoSmithKline, will begin human trials next week for an experimental Ebola vaccine in the hopes of rushing the drug as quickly as possible to health workers and others at risk in West Africa.

The early-stage human trial is set to begin next week at the National Institutes of Health Clinical Center in Bethesda and will test both the safety of the vaccine and its ability to generate an immune response in patients. The initial trial will include about 20 adults, and officials said they hope to have initial safety data by the end of the year — a scientific and ethical necessity before distributing any new drug widely.

“Safety is paramount; it’s absolutely paramount,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told reporters on a call Thursday. “The data [on the vaccine] in nonhuman primates is really quite impressive. But in science, you never know, and that’s why we do the trials.”

At the same time, the NIH and other groups, such as the British-based public health charity Wellcome Trust, are trying to line up similar human Ebola vaccine trials in the United Kingdom, Gambia and Mali beginning as early as next month.

Those trials could begin as soon as researchers receive ethical and regulatory approvals in each country. Fauci said that while it might be ideal to conduct trials in countries being hit hard by the current outbreak, such as Liberia or Sierra Leone, “the infrastructure in those places would not allow the kind of careful Phase I studies that you would like to do.”

As the worst Ebola outbreak in history unfolds in West Africa, The Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

The vaccine being tested at NIH next week is based on a chimpanzee cold virus called chimp adenovirus type 3. The virus is used as a carrier to deliver pieces of genetic material from two Ebola species: Sudan and Zaire, the type currently responsible for the devastating toll in West Africa.

The vaccine is designed to deliver one part of Ebola’s genetic material to human cells, eventually triggering an immune response in the patient. The vaccine, however, does not allow Ebola genes to replicate.

“It’s important to know that the Ebola genetic material contained in the investigational vaccine cannot cause a vaccinated individual to become infected,” Fauci said.

Officials said that if the trial proceeds as planned, the first wave of safety data could become available by year end. Should that prove promising, health workers on the front lines of the outbreak and others at risk of contracting the disease potentially could receive the drug sometime next year, though that timeline remains uncertain.

NIH’s trial comes amid a flurry of efforts to ramp up testing and production of various other treatments and vaccines developed in recent years, primarily by small biotech firms and governments such as the United States and Canada.

The urgency is understandable: The World Health Organization said Thursday that the worst Ebola outbreak in history is getting worse. The agency said the outbreak that has ravaged West Africa for most of this year ultimately could infect 20,000 people before it runs its course. So far, the virus has claimed 1,552 lives, and it shows little sign of slowing. More than 3,000 people officially have been infected in the current outbreak, but WHO officials believe that the real tally is likely much higher.

Fauci and other officials said Thursday that while the accelerated efforts to develop vaccines and treatments for Ebola could make a difference, the quickest way to slow the spread of the disease is to quarantine victims, trace and monitor their contacts and follow established sanitation and treatment practices.

View Graphic The Ebola epidemic over time

“Now, and in the immediate future, the real solution, if there is one, is to implement the public health measures” that have been proven to stop previous outbreaks, Fauci said. “In West Africa, these must be the main focus.”