Preliminary trials of a potential vaccine against the deadly Ebola virus have shown promising signs of building immunity against the deadly disease in those who have received the treatment.
The findings from two studies published Wednesday in the New England Journal of Medicine indicate the experimental vaccine known as rVSV-ZEBOV showed signs of the ability to provoke an immune response in recipients from Phase 1 trials conducted in the U.S., Africa and Europe between October and December 2014.
The vaccine candidate used for both sets of trials was co-developed by drugmakers NewLink Genetics Corp. and Merck & Co. It is derived from strains of the vesicular stomatitis virus, a common animal virus, to carry Ebola protein.
“The preliminary results reported here support the safety, side-effect profile, and immunogenicity of the rVSV-ZEBOV vaccine and encourage further investigation of this vaccine candidate,” the U.S. study concluded. “Live viral vaccines are generally associated with memory responses and long-lasting immunity; however, data regarding the duration of the protective response after vaccination with the rVSV vector are currently limited.”
For the U.S. trial, researchers from the Walter Reed Army Institute of Research in Silver Spring, Md., and the National Institutes of Health Clinical Center in Bethesda, Md., conducted a double-blind, controlled study that involved 52 adult volunteers. Six of the test participants received a placebo while the rest received various doses of the rVSV-ZEBOV.
In the international study, researchers tested 158 subjects in trials conducted at five sites, including the nations of Gabon and Kenya, as well as Germany and Switzerland. That study found that the treatment was "reactogenic but immunogenic after a single dose and warrants further evaluation for safety and efficacy.”
Eleven of the 51 participants in the Geneva, Switzerland, trial reported experiencing arthritis that affected one to four joints with pain lasting an average of eight days, but overall no deaths or serious adverse effects were reported in either study.
Common symptoms related to the vaccine in both sets of trials included fever, headache, muscle pain and fatigue that would last up to 36 hours after vaccination.
More than 10,000 deaths have been reported as a result of the Ebola virus outbreak in West Africa as of March 29, according to the latest figure from the World Health Organization.
“The ongoing Ebola outbreak in West Africa is unprecedented in scope and duration,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, in a statement released Wednesday. “The outbreak is slowly coming under control, thanks to extraordinary and multifaceted efforts in the affected nations. However, 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 underprepared for the next Ebola outbreak.”