Experimental Ebola vaccine shows promise, researchers say

An experimental Ebola vaccine tested on a group of American volunteers appears to be safe and triggers an immune response to the virus, scientists have found.

"The unprecedented scale of the current Ebola outbreak in West Africa has intensified efforts to develop safe and effective vaccines," said Dr. Anthony Fauci, director of the Bethesda, Maryland-based National Institute of Allergy and Infectious Diseases.

Fauci's institute, a division of the National Institutes of Health, and pharmaceutical giant GlaxoSmithKline developed the vaccine.

The clinical study of 20 volunteers, who are being monitored by medical investigators, was reported Thursday in the New England Journal of Medicine.

The vaccine was given to volunteers ages 18 to 50 in a trial designed to assess whether genes from two Ebola viral species can prompt an effective immune response.

Researchers determined the vaccine's effectiveness by testing volunteers' blood for signs of antibodies -- proteins that neutralize viruses.

Ten volunteers received the intramuscular injection at a lower dose and 10 at a higher one. Two weeks after vaccination, and again at four weeks, medical investigators tested volunteers' blood for anti-Ebola antibodies.

All 20 developed a healthy supply of antibodies within four weeks, with those receiving the higher dose having the highest antibody levels, researchers found.

Dr. Bruce Hirsch, a specialist in infectious diseases at North Shore University Hospital in Manhasset, said he hopes scientists are on the right track. At least one study has shown that antibodies can, in some rare instances, act as turncoats in Ebola disease and amplify the infection.

"We cannot say that just because they're antibodies and because antibodies are a good thing that this vaccine will be a positive treatment," Hirsch said. "There is a possibility that there may be adverse effects because, in some instances, antibodies may facilitate Ebola infection.

"We need to be open-eyed. We have to go to the next step and make sure that individuals who get the vaccine early on understand their risk and that we collect appropriate information so that we can serve the public good," he said. "Having an Ebola vaccine would be crucially important to control the spread of Ebola."

Hospitals on Long Island are continuing preparedness activities in the event an Ebola patient arrives at one of the facilities.

Word of the vaccine came as officials with the World Health Organization reported dynamic shifts in Ebola's West African epicenter. As infections appeared to be leveling off in several regions of the hardest-hit countries, Sierra Leone now accounts for more than half of all new cases, according to WHO.

Humanitarian groups in West Africa have been advocating for vaccines and other treatments because nothing exists to treat the thousands of people affected by the deadly virus.The organization estimates nearly 16,000 people have been infected since March and that 5,689 have died.

Scientists say the new candidate vaccine is composed of snippets of genetic material from two viral species -- Ebola Sudan and Ebola Zaire. The genetic material is incapable of causing an infection, but it allows the immune system to "see" the actual genetic signature of the Ebola virus and form antibodies to combat infection.Researchers have not yet determined how long inoculation against Ebola lasts. Dr. Daniel Bausch of Tulane University wrote in an accompanying commentary in the New England journal that additional questions about vaccine efficacy remain to be answered. However, having a candidate vaccine in hand, he concluded, is an important start.