01/06/2015 10:51 EST | Updated 03/08/2015 05:59 EDT

Ebola outbreak: 2-shot vaccine trial begins at University of Oxford

A third experimental Ebola vaccine will start safety testing in humans, a British university says.

Oxford University said Tuesday it aims to vaccinate 72 healthy adults with the experimental vaccine, developed by Johnson & Johnson, by the end of January. Some of the subjects will receive a placebo.

Unlike two other experimental vaccines, the J&J vaccine uses two separate injections. The "prime-boost" approach gives one shot to stimulate the immune system and a booster a few weeks later aims to enhance immune response over time.

The vaccine does not contain any replicating virus and can’t infect people with the Ebola virus that has killed more than 8,100 people, mainly in Guinea, Sierra Leone and Liberia.

"The main aim is to understand the safety profile of the vaccines," the study’s leader, Dr. Matthew Snape of the Oxford Vaccine Group, said in a release.

While public health measures remain the best way to bring the outbreak under control, Snape said, a safe and effective vaccine could start to help later this year. Further tests are planned later this month in the U.S. and soon after in Kenya, Uganda and Tanzania.

Earlier studies showed the prime-boost approach offered non-human primates complete protection against the Kikwit Zaire strain of Ebola that is similar to the virus causing the current outbreak, the university said.

J&J said it has produced enough vaccine to treat more than 400,000 people, which could be used in large-scale clinical trials by April.

How many doses are needed depends on how quickly the epidemic is brought under control.

Currently, experts project between 100,000 and 12 million doses could be needed.

A second experimental Ebola vaccine partly developed by researchers from Canada’s National Microbiology Laboratory is undergoing safety tests in Halifax and Geneva. The vaccine is licensed to NewLink and Merck.

Another experimental vaccine developed by GlaxoSmithKline and the U.S. National Institutes of Health is also in clinical development, including at Oxford.

Other vaccines are in development in Russia, the university said.