Experimental Ebola vaccines induce year-long immune response in Liberia trial

WASHINGTON, Oct. 12  — Two experimental Ebola vaccines can safely
elicit immune responses by one month after initial vaccination that last
for at least one year, results from a large clinical trial in Liberia
showed Wednesday.

The trial, published in the New England Journal of Medicine and conducted
by a U.S.-Liberia clinical research collaboration, involved 1,500 healthy
adults who were rapidly enrolled at Redemption Hospital in Monrovia, the
capital of Liberia, in early 2015 during the West Africa Ebola outbreak.
Three groups of 500 volunteers received one of the experimental vaccines or
a placebo, and they all provided blood samples before vaccination and again
at one week, one month, six months and one year post-vaccination. The
vaccines included cAd3-EBOZ, co-developed by the U.S. National Institute of
Allergy and Infectious Diseases (NIAID) and GlaxoSmithKline; and
rVSV-ZEBOV, which was initially engineered by scientists from the Public
Health Agency of Canada and is now licensed to Merck Sharp & Dohme Corp., a
subsidiary of Merck.

Blood sample testing showed that responses at one week were modest with
both vaccines but 71 percent of cAd3-EBOZ recipients and 84 percent of
rVSV-ZEBOV recipients developed an antibody response by one month. At one
year, 64 percent of cAd3-EBOZ recipients and 80 percent of rVSV-ZEBOV
recipients still had an antibody response, indicating that antibody
responses were largely maintained in both groups. Some participants who
received the investigational vaccines experienced mild to moderate side
effects that resolved, such as headache, muscle pain, feverishness and
fatigue. Overall, investigators did not identify any major safety concerns
related to the vaccines. Most of the serious medical issues reported during
the trial were due to malaria.”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,”
Anthony Fauci, director of the NIAID, which sponsored the trial, said in a
statement. “A safe and effective vaccine would be a critically important
addition to classical public health measures in controlling inevitable
future Ebola outbreaks,” Fauci said.Ebola virus disease is a severe, often
fatal illness in humans. The virus is transmitted to people from wild
animals and spreads in the human population through human-to-human
transmission. Currently, no Ebola vaccines have been licensed for use in
humans. – XINHUA