The first trial results of Ebola vaccine at Oxford University suggest the vaccine has an acceptable safety profile and is able to generate an immune response. “The Ebola vaccine was well tolerated. Its safety profile is pretty much as we had hoped,” said professor Adrian Hill of the Jenner Institute at Oxford University who led the trial. The results suggest that the vaccine is suitable for further testing in West Africa during the current outbreak.
The Ebola vaccine is being co-developed by the US National Institutes of Health (NIH) and pharmaceutical firm GlaxoSmithKline (GSK) against the Zaire strain of Ebola, which is the one circulating in West Africa. The first doses for use in large scale trials in West Africa have been delivered to Liberia by GSK. The vaccine uses a single Ebola virus gene in a chimpanzee adenovirus to generate an immune response.
As it does not contain infectious Ebola virus material, it cannot cause a person who is vaccinated to become infected with Ebola. During the trial, 60 healthy volunteers were vaccinated at the Jenner Institute. The results showed safety data and immune responses for the volunteers for 28 days after immunisation. Two people experienced a moderate fever within 24 hours of receiving the vaccine but this passed within a day. “People typically experienced mild symptoms that lasted for one or maybe two days, such as pain or reddening at the injection site, and occasionally people felt feverish,” professor Hill explained.
The primary goal of the trial was to assess safety. However, the scientists also assessed immune responses to Ebola seen in the volunteers before and after vaccination. Importantly, the vaccine generated immune responses against Ebola in the volunteers.
Levels of antibodies increased over a period of 28 days after vaccination and there was no significant difference in the levels seen at different doses. Levels of T cells – cellular immunity is the other arm of the body’s immune system – peaked at 14 days. “Larger trials in West Africa are needed to tell whether immune responses are large enough to protect against Ebola infection and disease,” the team added. The Oxford University trial is one of several safety trials of the GSK/NIH vaccine candidate – in the USA, Britain, Mali and Switzerland – that have been fast-tracked in response to the Ebola outbreak in West Africa.