Liz Szabo

USA TODAY

The USA will launch an early-stage trial in September of an experimental vaccine against Ebola, the deadly viral disease that has killed 729 people in the largest outbreak in history.

The National Institutes of Health has been developing an Ebola vaccine for several years that has had "encouraging results" in primates, says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. Fauci said he's working with the Food and Drug Administration to fast track the vaccine into a phase 1 clinical trial this fall. This type of trial is the earliest study in humans and aims to make sure that drugs are safe and show some efficacy.

Results from the study should be available by January, Fauci said. If the vaccine proves safe and effective, Fauci said he expects that it could be given to health workers in affected African countries sometime in 2015.

"We are starting to discuss some deals with pharmaceutical companies to help scale it up, so on an emergency basis, it might be available in 2015 for health workers who are putting themselves at extreme risk," Fauci said.

Ebola, which has a fatality rate of up to 90%, has infected more than 1,300 people in West Africa, including a number of health workers, according to the World Health Organization.

There are currently no effective treatments or vaccines for Ebola, which causes fever and headache in early stages but can lead to hemorrhaging, liver failure and kidney failure in later stages. But scientists have been working on four or five preventive vaccines that appear effective, said Thomas Geisbert, a professor at the University of Texas Medical Branch in Galveston.

The only positive development to come from the epidemic is that it's attracted long-needed attention from drug makers, Fauci said.

"We have been working on our own Ebola vaccine, but we never could get any buy-in from the companies," he said.

For years, pharmaceutical companies have seen little potential for profit in Ebola, because outbreaks are unpredictable and typically small, Geisbert said.

"It's not like cancer or heart disease, or even a prevalent infectious disease like malaria," he said.

Until the current outbreak, many people believed there wasn't a great need for an Ebola vaccine, because the virus would cause only 10 to 100 cases a year, says Scott Lillibridge, assistant dean at the Texas A&M School of Public Health, who served as medical director of the U.S. Office of Foreign Disaster Assistance during the Ebola outbreaks in the 1990s.

"In the past, it was felt that this was something we could treat with hospital infection control," Lillibridge says. "The current outbreak has somewhat changed our thinking."

Now, more people believe that the world needs an Ebola vaccine. If countries don't vaccinate their entire populations, many will want to protect health workers in hospitals and clinics from contracting and spreading the virus, Lillibridge says.

The Food and Drug Administration has made exceptions to its usually stringent rules for drug development when considering treatments for Ebola and other rare and lethal diseases, Geisbert said.

The NIH recently gave Geisbert's lab a five-year, $26 million grant to research three of the most promising treatments for Ebola. These include a man-made antibody treatment; a promising Canadian drug from Tekmira Pharmaceuticals shown to protect monkeys from Ebola; and a vaccine that can be used both to prevent infection and also treat it.

"One of our goals is to start combining these treatments, like we do with AIDS medications," Geisbert said.

He said there are a number of obstacles to bringing these drugs to the clinic.

"It's a very fast-moving disease, and you often don't have a lot of time to intervene," Geisbert said. "If someone has full-blown Ebola hemorrhagic virus, there is no drug on the planet that is going to protect them. But in the monkey model, we do have drugs where, if you have an early stage of infection and an early stage of illness, some of them are pretty successful."

Developing effective treatments is growing more important by the day, as the West African outbreak grows. In the past, public health officials were able to get control of Ebola outbreaks by quarantining the small, remote towns and villages where they occurred, he said.

Quarantining large populations in more densely populated cities, where Ebola is now occurring, is far more difficult, Geisbert said.

The current outbreak is also harder to manage because the disease is popping up in so many places at once. That makes it harder to concentrate health experts and specialists in one area. "It's spreading the experts who know how to manage these things pretty thin," he said.