Experts involved in the organisation of clinical research on Ebola vaccines intend to move to randomised controlled phase II trials in early 2015, once safety data from phase I trials become available as early as November 2014.
The two candidate vaccines are the cAd3-ZEBOV, made by GlaxoSmithKline (GSK), which uses a chimpanzee-derived adenovirus vector with an Ebola virus gene inserted, and rVSV-ZEBOV by Newlink Genetics Corp, which uses an attenuated or weakened vesicular stomatitis virus, a pathogen found in livestock, where one of its genes has been replaced by an Ebola virus gene.
Vaccine doses are expected to be available for the phase II trials in January 2015, according to the World Health Organization (WHO).
Vasee Moorthy, a WHO clinical trialist, said that experts have agreed that there will be two sets of phase II trials running in parallel.
Under the plan, a group of studies will involve about 3,000 people in neighbouring countries in West Africa, reflecting a broad sample of the population. In parallel, another trial involving about 5,000 people in prospective cohort trials, will cover the three most affected countries — Liberia, Guinea, Sierra Leone — involving people who work in treatment facilities and who are considered to be at high risk of getting the virus, said Moorthy.
WHO said at the end of an expert meeting held on 29-30 September that the Ebola vaccines will be tested through randomised controlled trials (RCTS) as they provide the most robust data, but added that alternative designs “should be considered” when RCTs are not viable.