More than 6,000 people have already died due to the Ebola outbreak, and it does not look like the virus is done. Thousands more remain infected, hoping for a cure that is still being developed. However, human testing is underway with good news that clinical trials are producing positive results.

According to the National Institutes of Health, clinical trials started in September and were verified in November, generating positive responses from the volunteers' immune systems while manifesting few side effects. For this clinical trial, genetic material from two strains of the Ebola virus, Sudan and Zaire, were used for the vaccine, with injections delivered via a carrier virus derived from a chimp adenovirus.

Within four weeks, antibodies were produced by all of the volunteers. Two developed fevers briefly after receiving a shot of the vaccine but no other side effects were reported. Aside from antibodies, the vaccine also spurred the production of T-cells, white blood cells critical to immune system health.

"Based on these positive results from the first human trial of this candidate vaccine, we are continuing our accelerated plan for larger trials to determine if the vaccine is efficacious in preventing Ebola infection," said Anthony Fauci, National Institute of Allergies and Infectious Disease head.

This clinical trial is Phase 1 for a vaccine being developed by GlaxoSmithKline. Additional safety trials are being done in Switzerland and Mali while Phases 2 and 3 are scheduled to be held in West Africa. In January, a clinical trial will be carried out in Liberia to test the vaccines being made by GlaxoSmithKline and American company NewLink Genetics.

However, as this Phase 1 trial concludes on a positive note, scientists are still facing a problem: should Ebola vaccines be delivered in one or two shots?

The upside to a single-shot vaccine is that it can be administered more easily. Two shots, on the other hand, would be more difficult to produce but once given will provide better protection against the Ebola virus.

What defines better protection?

Two-shot vaccines tested for other diseases showed that the booster component to the vaccine can promote immune system response, producing up to 30 times more antibodies and 10 times more T-cells.

Should two-shot vaccines be used in West Africa, the extra protection afforded by the booster component will be helpful in keeping other conditions at bay as well such as Malaria which can take a toll on the immune system, reducing the effectiveness of an Ebola vaccine.

The clinical trial set for Liberia in January will test single shots of two Ebola vaccines and a placebo.

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