US to Test Ebola Vaccine in Humans Amid Growing Outbreak in West Africa

U.S. scientists will begin testing an Ebola vaccine in humans next week, health officials announced today. But it could take 11 months to learn whether the vaccine is safe as the virus' toll in West Africa continues to rise.

More than 3,000 people have contracted Ebola since March, a number projected to swell to 20,000 in the next six months, according to the World Health Organization.

The virus has killed at least 1,500 people in Ebola Liberia, Guinea, Sierra Leone and Nigeria.

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The experimental vaccine, co-developed by the National Institutes of Health and GlaxoSmithKline, "performed extremely well in protecting nonhuman primates from Ebola infection," Dr. Anthony Fauci, director of the NIH's infectious disease branch, said.

Now it will be tested in 20 healthy adults to make sure it's safe and effective in mounting an immune response.

"A vaccine will ultimately be an important tool in the prevention effort," Fauci said in a statement today, adding that the phase 1 study is "the first step in a long process."

The 20 subjects will be followed for 48 weeks but initial safety results are expected later this year, according to an NIH statement.

The vaccine works by delivering fragments of genetic material from two Ebola strains into a healthy person's cells. The cells then transform that genetic material into a protein found on the virus, and that protein triggers an immune response that should fend off the infection.

"It is important to know that the Ebola genetic material contained in the investigational vaccine cannot cause a vaccinated individual to become infected with Ebola," the NIH said in a statement.

Another experimental Ebola drug known as ZMapp has been used in six people, including American aid workers Dr. Kent Brantly and Nancy Writebol. The drug is not a vaccine, but contains synthetic antibodies designed to mimic the body's immune response.