VSV-Ebola vaccine appears to be safe

Initial results from the Phase 1 trials of the candidate Ebola vaccine rVSV ZEBOV suggest that the vaccine is safe and generates an immune response. The research, published in the New England Journal of Medicine, was carried out at the KEMRI|Wellcome Trust in Kilifi (Kenya), and three other sites in Switzerland, Germany and Gabon.

The candidate vaccine was given to 138 volunteers across the four sites.  No serious side effects were seen among the volunteers.  Some of the volunteers experienced fever for the first few days after vaccination, and some developed transient pain and/or swelling of their joints. The candidate vaccine was also able to raise antibody responses that neutralized Ebola-like virus particles in the laboratory.

Dr Jeremy Farrar, Director of the Wellcome Trust, said: “It’s very encouraging to see further evidence of the safety of the rVSV-ZEBOV vaccine. What we don’t yet know is whether this vaccine will be able to prevent people from becoming infected with Ebola. The large-scale ring vaccination currently underway in Guinea gives us the best possible chance of achieving a definitive answer to that question. It is absolutely essential that the vaccine study in Guinea is completed as soon as possible, and if the vaccine proves to be safe and effective it is used immediately to bring this disastrous epidemic to an end.”

The vaccine has now gone forward to testing in a Phase III ring vaccination study in Guinea (one of the countries affected by the Ebola outbreak) to see if it protects those at risk of infection (https://time.com/3758011/ebola-vaccine-trial-guinea/). The rVSV ZEBOV vaccine is made by combining the Vesicular Stomatitis Virus (VSV) with a portion of a single protein covering the Ebola virus. Giving a person the vaccine cannot cause them to become infected with the virus.

In Kenya, the study was facilitated by KEMRI scientific and ethical review and the regulatory agency the Pharmacy and Poisons Board under the Ministry of Health, which fast-tracked reviews to condense a 6 month process down to 6 weeks. The trial team in Kilifi was led by Dr. Patricia Njuguna with support from Prof Philip Bejon and Dr Benjamin Tsofa.

The vaccine trial was part of a wider World Health Organization (WHO) led consortium (VEBCON) which is funded by the Wellcome Trust. Although there are no cases of Ebola reported in Kenya, demonstrating safety and immune responses by the vaccine in the Kenyan population will facilitate use of the vaccine if necessary.