Two experimental Ebola vaccines produced significant immune responses among participants in a large, randomized, placebo-controlled clinical trial, according to a study published in The New England Journal of Medicine.
From Feb. 2, 2015, through April 30, 2015, researchers enrolled 1,500 adults with no reported history of Ebola virus at Redemption Hospital in Monrovia, Liberia. The participants received treatment with one of two vaccine candidates or a placebo.
One month after vaccination, blood samples from 71 percent of participants given a vaccine co-developed by National Institute of Allergy and Infectious Diseases of the National Institutes of Health displayed Ebola antibodies. Blood samples from 84 percent of participants administered a vaccine licensed by Merck Sharp & Dohme Corp., displayed Ebola antibodies. Among the placebo group, just 3 percent displayed Ebola virus antibodies. At one year post inoculation, 64 percent of the NIH-backed vaccine cohort and 80 percent of the Merck-licensed vaccine cohort still displayed an Ebola antibody response.
Investigators did not identify major safety concerns during the study. Some participants experienced moderate to mild side effects such as headache, muscle pain, fever and fatigue.
"This clinical trial has yielded valuable information that is essential for the continued development of these two Ebola vaccine candidates and also demonstrates that well-designed, ethically sound clinical research can be conducted during an epidemic," said Anthony S. Fauci, MD, director of the NIAID. "A safe and effective vaccine would be a critically important addition to classical public health measures in controlling inevitable future Ebola outbreaks."
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