Ebola Vaccine Shows Promising Outcomes in Initial Human Trials

The outcomes of a small study of an experimental Ebola vaccine in human beings reveals that it seems safe, provides an immune response and is well accepted, prompting support for its development to be fast-tracked.

The candidate vaccine is being combined developed by the National Institute of Allergy and Infectious Diseases (NIAID) and GlaxoSmithKline (GSK).

A primary report on the VRC 207 trial, which examined the safety of the vaccine in 20 healthy subjects at the NIH Clinical Center in Bethesda, is presented in the New England Journal of Medicine.

The unprecedented scale of the present Ebola outbreak in West Africa has motivated powerful efforts to produce safe and effective vaccines, not just to help stem the present spread, but also to stop future outbreaks.

“Dependent on these favourable outcomes from the initial human trial of this candidate vaccine, we are carrying on our more rapid plan for larger studies to identify if the vaccine is effective in stopping Ebola infection,” states NIAID Director Dr. Anthony S. Fauci.

Vaccine consists of genetic material from two strains of Ebola

The vaccine consists of a safe “carrier virus” – which leads to a common cold in chimpanzees and does not lead to illness in human beings – and genetic material from two strains of Ebola virus (the Sudan strain and the Zaire strain).

The vaccine does not consist of Ebola virus and can’t lead to Ebola disease, say the developers.

In overall, 20 healthy subjects older 18-50 volunteered for the study. Of these, 10 individuals got a low dose, and 10 got a high dose of the vaccine via intramuscular injection.

The investigators examined the individuals’ blood 2 weeks and 4 weeks later on to find out if the vaccine had triggered their immune systems to develop antibodies to Ebola.

The outcomes demonstrated that all the individuals had developed anti-Ebola antibodies at the 4-week point. The maximum levels of antibodies were identified in the subjects who obtained the greater dose of vaccine.

Vaccine also prompted T-cell reaction

The outcomes also demonstrated presence of CD8 T-cells in the blood of two subjects in the low-dose group and 7 in the high-dose group. These cells are developed by the immune system and may be an essential part of immune protection towards Ebola, note the investigators.

Lead researcher Julie E. Ledgerwood, a investigator at the NIAID Vaccine Research Center, describes:

“We know from earlier research in non-human primates that CD8 T-cells performed a essential role in defending animals that had been vaccinated with this NIAID/GSK vaccine and then subjected to otherwise lethal quantities of Ebola virus.

The size and quality of the CD8 T-cell reaction we noticed in this study are very similar to that noticed in non-human primates vaccinated with the candidate vaccine.”

The scientists noticed no serious adverse effects of the vaccine in any of the subjects, even though two who had the greater dose did have a short fever the day after getting the injection.

Study delivers Ebola vaccine ‘one step closer’

While the study outcomes are favourable and ensuring, there are still many concerns to answer prior to the vaccine can be viewed as effective. Part of the issue is that it is not clear what comprises an effective level of immunity.

Other studies are taking place that may answer some of the unresolved concerns, says Daniel D. Bausch, an associate professor at Tulane University School of Public Health and Tropical Medicine, in an editorial associated with the study report. He adds:

“The path is even now lengthy and there are a lot of difficulties, but we are however one step closer to a solution.”

Prof. Bausch states that while there is room for careful optimism as the Ebola epidemic obviously slows down in some areas of West Africa, there are even now pockets of intense transmission, and reviews demonstrate the outbreak is now distributing into Mali.

These events “point out to us that the fight for control is however on. This is no time to be satisfied,” he urges.