Experimental Ebola Vaccine Shows Acceptable Safety, Ability to Generate Immune Response

An experimental Ebola vaccine, which has its first trials at Oxford University has shown an acceptable safety profile as well as the ability 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.

However, the trial was conducted in 60 healthy volunteers, who were vaccinated at the Jenner Institute. After immunisation, the results showed safety data and immune responses for the volunteers for 28 days.

Meanwhile, though two people experienced a moderate fever within 24 hours of receiving the vaccine, the fever 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. Also, it has 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 are 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.

The initial findings were published in the New England Journal of Medicine (NEJM).


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