Experimental Ebola vaccine found safe, effective

An early-stage clinical trial has found that an experimental Ebola vaccine is safe and elicited robust antibody responses in all 40 of the healthy adults who received it, scientists say.
The most common side effects of the vaccine, called VSV-ZEBOV, were injection site pain and transient fever that appeared and resolved within 12 to 36 hours after vaccination.
The VSV-ZEBOV candidate is one of two experimental Ebola vaccines now being tested in the phase 2/3 PREVAIL clinical trial that is enrolling volunteers in Liberia.
"There still are no licensed specific therapies or vaccines for Ebola. Until a safe and effective vaccine is available, the world will continue to be under-prepared for the next Ebola outbreak," said Anthony S Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of National Institutes of Health (NIH).

Scientists at the Public Health Agency of Canada developed the candidate vaccine. It was licensed to NewLink Genetics Corp of Ames, Iowa.
The investigational vaccine is based on a genetically modified and attenuated vesicular stomatitis virus (VSV), a virus that mainly affects cattle.

In the investigational vaccine, a gene for a VSV protein is replaced with a gene segment from a key protein in the Zaire species of Ebola virus.
The vaccine does not contain the whole Ebola virus and therefore cannot infect vaccinated persons with Ebola.
A new report published in The New England Journal of Medicine summarises results of the first 52 volunteers enrolled in the study: 26 at the NIH Clinical Center in Bethesda, Maryland, and 26 at the Walter Reed Army Institute of Research (WRAIR) clinic in Silver Spring, Maryland.

Six volunteers at each site received a placebo injection of saline solution, and the remaining 40 received the experimental vaccine at either one of two different dosages.
The candidate vaccine's ability to stimulate immune responses was assessed by sampling the volunteers' blood at multiple time points following injection.
Of those volunteers tested at 14 days after injection, 93 per cent (26 out of 28) of whose who had received vaccine developed antibodies against Zaire species of Ebola virus.
Antibodies were detected in the remaining 14 volunteers who had received vaccine by 28 days after injection. Antibody responses were approximately three-fold greater in those who received the higher vaccine dose.

"The prompt, dose-dependent production of high levels of antibodies following a single injection and the overall favourable safety profile of this vaccine make VSV-ZEBOV a promising candidate that might be particularly useful in outbreak interventions," said NIAID investigator Richard T Davey.