In the race to stop the Ebola virus in its tracks, a vaccine that would help prevent people from contracting the deadly disease would be a powerful weapon.
Yet a vaccine still seems far off, even though global health officials are urging countries and companies to fast-track efforts to develop one, without compromising safety and effectiveness.
And there's the rub. Safe and effective vaccines are difficult and expensive to develop in the best of times. That process is more challenging in the midst of a growing health crisis.
Even the medicines being tested to treat a patient already diagnosed with Ebola offer no easy solutions.
Thomas Eric Duncan, the Liberian man who is undergoing treatment for Ebola and listed in serious condition in Dallas, won't be getting the experimental drug ZMapp used on several international aid workers and medical staff, including at least two other Americans.
That's because the company that makes ZMapp, Mapp Biopharmaceutical, has run out of supplies.
This just highlights how difficult it is to develop new medicines, said Dr. Pascal James Imperato, dean of the School of Public Health at SUNY Downstate Medical Center.
"It would be great to have a vaccine but it takes time to develop these treatments and there are the technical hurdles like testing to go through."
"It would be great to have a vaccine but it takes time to develop these treatments and there are the technical hurdles like testing to go through," Imperato said. "It's just not that easy to make them."
Imperato added that even coming up with a vaccine may not do the trick. That's because Ebola has so many mutating strains, making it much more difficult to find one drug that fits all.
Pressure for Vaccine
Duncan's case could raise the pressure to find a vaccine, but the rush could do more harm than good, said Dr. Robert Quigley, U.S. medical director and senior vice president of medical assistance for International SOS.
"We have to make sure a vaccine works and that takes time," Quigley said. "The side effects could be more harmful than realized."
There are a few small American companies developing Ebola treatments, such as BioCryst and NanoViricides.
One Canadian firm, Tekmira, is also working on a treatment, with funds from the U.S Defense Department.
Last month NewLink Genetics said it would start safety testing of a vaccine within a few weeks, while Inovio Pharmaceuticals said it would start human trials of a DNA-based vaccine in early 2015.
Most of the larger outfits have shied away because of the expense and time involved in getting a vaccine on the market.
"It's tough to develop these drugs because they might not even be used," said Dr. Chris Milne, director of research at the Tufts Center for the Study of Drug Development.
Milne said that pharmaceutical companies can spend millions in developing vaccines like for the flu, that get thrown away because they're ineffective on new virus strains.
"It's a lot of time, effort and money to develop something like an Ebola vaccine with little guarantee of a profit," he said.
GlaxoSmithKline and the National Institutes of Health have recently partnered on an Ebola vaccine that has entered Phase 1 clinical trials.
"We got approval to get the process going within 48 hours from the Federal Drug Administration when it normally takes 30 days," said Dr. David Vaughn, head of GlaxoSmithKline's external research and development, North America.
Vaughn said the the vaccine was first developed at the European company Okarios, which Glaxco bought in 2013. Vaughn couldn't say when the vaccine might be available for general use but said that GlaxoSmithKline is "going as quickly as we can without compromising the safety" of the vaccine.
Is ZMapp Effective?
As for ZMapp, the jury is still out on it's effectiveness. A doctor in the West African nation of Liberia who had Ebola died despite taking it.
"It's too early to say if ZMapp worked or not," said SUNY's Imperato. "The patients who got it and survived underwent other treatment and that may have helped them just as much as the drug."
Ebola is believed to have sickened more than 6,500 people in West Africa, and over 3,000 people have died.
That's spurred calls for action. The World Health Organization (WHO) is urging international efforts to develop an Ebola vaccine "within a matter of months ... without compromising international standards for safety and efficacy."
President Barack Obama on Tuesday discussed "stringent isolation protocols" with the head of the Centers for Disease Control (CDC) to limit the risk of more Ebola cases after the diagnosis in Dallas.
The United States is deploying 3,000 soldiers to build treatment center and train local medics in West Africa. Other nations, including Britain, France, China and Cuba, have pledged military and civilian personnel alongside cash and medical supplies.
Meanwhile, the World Health Organization has said the total number of infections could reach 20,000 by November, months earlier than previously forecast.
The CDC recently warned between 550,000 and 1.4 million people might be infected in West Africa by January if nothing is done.
But even if a vaccine is available, it's not for everyone, said International SOS' Quigley.
"It's not like getting a flu shot," he said. "It should only be available for those at risk, like health-care workers and those who live and are traveling in the areas of outbreak."