Phase II trial for Ebola vaccine

DEVELOPMENT of vaccines against Ebola virus has been fast tracked since the World Health Organisation declared the Ebola virus outbreak a public health emergency in August 2014. Among these vaccines is the “rVSV-ZEBOV-GP” developed at St. George’s, University of London, which is now being tested in a larger population to examine the efficacy of this vaccine.

 

Professor Sanjeev Krishna, of the university’s Institute for Infection and Immunity, said there has not been such urgency to deliver a viable vaccine or treatment since the coming together of medical experts in the early 1980s tackling HIV.

 

Collaboration with other researchers of an international consortium (VEBCON) provided results essential to begin a clinical trial to test the vaccine in Guinea. The initial study, which tested the safety, tolerability and immunogenicity of the vaccine, vaccinated the first volunteer in November 2014. Volunteers in Kenya, Gabon, Switzerland and Germany participated in this harmonized phase I clinical trial*.

 

The rVSV-ZEBOV-GP vaccine, which is named after its components, carries only one protein (GP) from the Zaire strain of the Ebola virus (ZEBOV) on the surface of a different virus (VSV) that infects cows, horses, pigs and insects. The Ebola virus protein by itself is not able to cause any disease, and VSV only causes minimal illness in humans.

 

Currently, it is the only vaccine against Ebola virus disease in clinical trials that is made from a replicating virus. The advantage of this type of vaccine is that the immune system may develop an effective protective response to Ebola virus, and it allows the use of a lower dose of vaccine. Furthermore, only one shot of vaccine may be required, minimising the number of visits to healthcare workers needed to develop protection.

 

Early results are promising

 

The progress of the clinical trials is very promising and the rVSV-ZEBOV-GP vaccine adds significantly to the options available for testing against Ebola virus, Professor Krishna said.

 

“Although cases of Ebola virus disease are now decreasing, the outbreak has left an appalling legacy. If a vaccine had been available, the health workers tackling this scourge could have been protected. We still urgently need a safe and effective vaccine to protect people in the future. This research works towards meeting that need,” he said.

 

The consortium examining the Ebola virus vaccine is led in CERMEL in Gabon, coordinated by Dr Selidji Agnandji, and by Professor Peter Kremsner in their partner institute at University of Tübingen in Germany.

 

Professor Krishna acts as a scientific advisor to the consortium, and was among a consortium of experts convened by the WHO, in September 2014 in Geneva, to discuss solutions and strategies for combatting the current Ebola virus crisis. The candidate vaccine is called rVSV-ZEBOV-GP and was developed by the Canadian Public Health Agency and produced by the US firm NewLink Genetics.   

 

* Selidji T. Agnandji, M.D., Angela Huttner, M.D., Madeleine E. Zinser, M.D, et al "Phase 1 Trials of rVSV Ebola Vaccine in Africa and Europe — Preliminary Report." New England Journal of Medicine