GENEVA The clinical trial of an Ebola vaccine developed by Merck and NewLink resumed on Monday at a lower dose after a pause to assess complaints of joint pains in some volunteers, the University of Geneva hospital said.
An Ebola outbreak, the worst on record of the highly infectious hemorrhagic fever, has killed over 7,900 people over the past year, with more than 20,000 cases recorded mostly in Guinea, Sierra Leone and Liberia, according to the World Health Organization (WHO). The virus is still spreading in West Africa, especially in Sierra Leone.
The Geneva hospital announced on Dec. 11 that its vaccine trial had been suspended as a precautionary measure after four patients complained of joint pains. On Monday, the hospital said 10 of 59 volunteers who received the vaccine had felt pains in their joints "similar to rheumatism" after some two weeks, but these symptoms had disappeared rapidly without any treatment.
Swissmedic, the Swiss regulatory agency, and ethics and safety committees have approved the resumption of the trial at a lower dose, the hospital said in a statement.
"The second part of this clinical trial will now test a dose of 300,000 vaccine particles, which should be better tolerated by volunteers and will hopefully trigger the production of enough antibodies," it said, noting that the initial phase had 10 million to 50 million vaccine particles.
"Fortunately", it said, the Merck-NewLink candidate vaccine "seems able to induce the production of antibodies at lower doses than those previously used" in the Geneva trial.
Vaccinations have now resumed for the last 56 volunteers, who will receive either a low dose of the vaccine or a placebo, by groups of 15 each week through January, it said.
Geneva researchers are constantly exchanging information with teams carrying out similar studies in Canada, Gabon, Germany and the United States, the hospital said. Final results are expected in March 2015.
A separate trial of a GlaxoSmithKline Ebola vaccine on 120 volunteers has proved "satisfactory", the University of Lausanne Hospital said on Dec. 11.
(Reporting by Stephanie Nebehay; Editing by Mark Heinrich)