Ebola vaccine performs well in tests on monkeys, scientists say

Tests of an experimental Ebola vaccine have shown positive results, protecting healthy monkeys from the virus, researchers say, as West Africa grapples with an epidemic that has killed about 2,000 people.

Researchers gave four macaque monkeys a shot of the experimental vaccine, called ChAd3, and exposed them to high levels of the Ebola virus five weeks later. All the monkeys were protected, the National Institute of Allergy and Infectious Diseases said on Sunday.

The protection decreased over time, however: Ten months after receiving the vaccine, just two of the four were protected.

Researchers also gave monkeys the experimental vaccine and then, eight weeks later, a booster vaccine. Ten months after the initial dose, all four monkeys were fully protected.

The authors of the latest study, published in Nature Medicine, suggested that without the booster, the Ebola virus could quickly regain a foothold.

Human trials of the ChAd3 vaccine were scheduled to start last week in the US state of Maryland with preliminary results due by the end of the year. In the current crisis, US officials overseeing the trials suggested that the availability of a tested vaccine would offer some assurance of protection to health-care workers wary of going to West Africa.