The Food and Drug Administration has authorized use of an unapproved Ebola virus test under a special emergency-use provision, although efforts to develop a vaccine for the deadly illness are unlikely to bear fruit until 2015, officials say.

The test-tube diagnostic test was developed by the U.S. military and is used to detect the Zaire strain of Ebola, which has infected at least 1,711 and killed 932 in West Africa.

"The test is designed for use in individuals, including Department of Defense personnel and responders, who may be at risk of infection as a result of the outbreak," FDA spokeswoman Stephanie Yao said in a statement.

"Specifically, the test is intended for use in individuals with signs and symptoms of infection with Ebola Zaire virus, who are at risk for exposure to the virus or who may have been exposed to the virus."

Although health officials insist the chances of an Ebola virus outbreak in the U.S. are extraordinarily low, the admission of two infected aid workers to a special containment unit at Emory University Hospital in Atlanta has sparked fears among the public.

On Wednesday, officials at New York’s Mount Sinai Hospital said a patient who was admitted after complaining of early Ebola-like symptoms has tested negative for the virus.

Initially, infection will cause flu-like symptoms such as fever, vomiting, muscle aches and weariness. As the virus continues to multiply and damages the cells that line blood vessels, patients will suffer bleeding and possible organ failure.

In this latest West African outbreak, the virus has killed roughly 55 percent of those infected, experts say.

As a result of the outbreak, the FDA has given special fast-track approval status to a number of vaccines that are still being tested.

"There are a few vaccines in the pipeline," said Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases.

Vaccines work by exposing the body to foreign microbes or substances that simulate an attack on the body, and essentially train the immune system to defend itself against a real, future invader such as the Ebola virus.

For a vaccine to work properly, it must be administered prior to infection and given time to work.

The vaccines now under development are not the same type of experimental drug that was given to a pair of American aid workers infected in Liberia. That drug, called ZMapp, is being developed by Mapp Pharmaceutical Inc., and is a mix of three monoclonal antibodies produced in plants. It is intended to be given to patients shortly after they become infected.

The experimental vaccine that is furthest ahead in the development process was designed by the Vaccine Research Center, an arm of the National Institutes of Health.

"We’ve tested it in monkeys," Fauci said. "The results were quite impressive."

Phase 1 clinical trials are expected to begin in late September and run until January, Fauci said. During that time, researchers will give the vaccine to humans to determine whether it is safe, and whether it prompts a protective response. In this case, a protective response would be the production of special antibodies that prevent the Ebola virus from attaching to and entering the body’s cells.

Unlike animal tests, where monkeys are actually infected with Ebola to determine the drug’s effectiveness, human test subjects will not be infected with the disease.

If the vaccine is shown to be safe, and induces a protective response, research will progress to larger clinical trials and then to production of the vaccine.

"I would hope that we have something by the end of 2015," Fauci said. "Even fast-tracking it, it might take that long."

The first recipients of an approved vaccine would likely be health care providers who work with Ebola patients, as they face the greatest risk of infection. (The virus is transmitted through bodily fluids.)

In addition to the Vaccine Research Center’s proposed vaccine, the NIH is also supporting the Crucell biopharmaceutical company in the development of a vaccine for the Ebola and Marburg viruses as well as Profectus Biosciences in its development of an Ebolavaccine.

The NIH said it was also working with Thomas Jefferson University "to develop a candidate Ebola vaccine based on the established rabies vaccine."

"Two other companies, Tekmira and BioCryst Pharmaceuticals, receive funding from the Department of Defense’s Defense Threat Reduction Agency and have therapeutic candidates for Ebola in early development," read a statement from the U.S. Department of Health and Human Services.

"The Department of Defense is working with a company called Newlink to develop an Ebola vaccine candidate. BioCryst, with NIH support, is working to develop an antiviral drug to treat Ebola virus that is expected to begin Phase 1 testing later this year."