Canadian Medical Association Journal
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A phase 1 randomized controlled trial has found an Ebola virus
disease (EVD) vaccine, developed in Canada, was well-tolerated with no
safety concerns, and high antibodies were present in participants 6
months after immunization. The study, led by Canadian researchers, is
published in CMAJ (Canadian Medical Association Journal).
The research team conducted the clinical trial "as part of a
coordinated, international effort to expeditiously evaluate candidate
EVD vaccines and make them available to control the epidemic," writes
lead author Dr. May ElSherif, Canadian Center for Vaccinology, IWK
Health Centre, Halifax, Nova Scotia, with coauthors.
There have been some recent clusters of Ebola cases in Africa and
more expected as survivors may still spread the virus to uninfected
people.
The trial involved 40 healthy people aged 18 to 65 years and looked
at safety of the vaccine and the lowest dose required for an immune
response after injection with one of 3 doses. At a ratio of 3:1, thirty
participants received the vaccine and 10 received placebo injections.
The researchers found that adverse events were mild to moderate, with
only 3 severe reactions, including headache, diarrhea and fatigue, which
completely resolved.
"The results of this trial were positive and very promising; all 3
dose levels of the VSV [vesicular stomatitis virus] Ebola vaccine were
well-tolerated by participants, and no safety concerns were identified,"
says Dr. May ElSherif.
Several Ebola vaccine candidates are being assessed in ongoing or
recently completed phase 1, 2, and 3 trials in various parts of the
world. This VSV-Ebola vaccine (formal name: rVSVΔG-ZEBOV-GP) was
developed at the Canadian National Microbiology Laboratory of the Public
Health Agency of Canada. A similar parallel trial was conducted at the
Walter Reed Army Institute of Research (WRAIR) in the United States.
Wild type VSV primarily infects animals (e.g., cattle and horses) and rarely infects humans.
Data from this trial and others indicated an optimum dose of 20
million pfu that will be assessed among people with compromised immune
systems in areas where Ebola is endemic. An upcoming study at 2 sites in
Africa, as well as in Montréal and Ottawa in Canada, will test the
safety and protection levels of the VSV-Ebola vaccine in HIV-infected
adults and adolescents. A completed phase 3 trial showed that the
vaccine is effective in preventing EVD in contacts of recently confirmed
cases.
Given the ongoing presence of Ebola, "these facts underscore the
importance of continuing efforts and collaborations that may ultimately
lead to licensed Ebola vaccines that would protect humans and prevent or
control outbreaks in the future," conclude the authors.
The study was conducted by researchers from the Canadian
Immunization Research Network (CIRN) at the Canadian Center for
Vaccinology at the IWK Health Centre and Nova Scotia Health Authority,
Dalhousie University, Halifax, Nova Scotia; National Microbiology
Laboratory, Winnipeg, Manitoba; Battelle Biomedical Research Center,
Columbus, Ohio; United States Army Medical Research Institute of
Infectious Diseases and the Joint Program Executive Office for Chemical
and Biological Defense Medical Countermeasure Systems' Joint Vaccine
Acquisition Program, Fort Detrick, Maryland; BioProtection
Systems/NewLink Genetics Corporation, Ames, Iowa; and Veristat LLC,
Southborough, Massachusetts.
source:eurekalert.org
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