President Barack Obama has sought to assuage fears about Ebola in the face of panic and misinformation. In his Oct. 18 weekly address , he called on people to "be guided by the science and "remember the basic facts."

"Ebola is actually a difficult disease to catch," Obama said. "It's not transmitted through the air like the flu. You cannot get it from just riding on a plane or a bus."

That last line, repeated often by the administration in various forms, has caught the ire of critics, who believe the statement is too cavalier. It’s also at odds with some advice from health officials that people who may have been exposed to the virus should avoid public transportation.

So we decided to take a look at it ourselves: Can you get Ebola from "just riding" on a plane or a bus?

As Thomas Fekete, a professor of infectious diseases at the Temple University School of Medicine, told us, "There is no ‘infection free’ zone just because you're on a bus or a plane."

However, Fekete and others said the likelihood that someone would contract Ebola while flying or using public transportation is small. Extremely small. It would take a lot more than just sitting next to or sharing air with an infected individual.

Let’s explain.

How Ebola spreads

People infected with the virus are not contagious until they are showing symptoms, according to experts and research. Symptoms are, first, a fever, followed by vomiting and diarrhea, which usually occurs between 2 and 21 days of contracting the virus.

Risk of contracting Ebola is greatest if you come in direct contact with "blood, secretions, organs or other bodily fluids of infected people," according to the World Health Organization. These fluids contain high concentrations of the virus that can result in infection if they are exposed to your eyes, mouth, nose or a cut on your skin, even for a relatively short amount of time.

There is also some risk, albeit low, that the virus can be spread by "being within approximately 3 feet of an (Ebola) patient or within the patient’s room or care area for a prolonged period of time," or by touching surfaces contaminated by bodily fluids of an infected patient.

However, there is little evidence to date that Ebola spreads this way. Studies from previous Ebola outbreaks show that "all cases were infected by direct close contact with symptomatic patients," the World Health Organization noted.

What the government says

Some critics say that Obama and the Centers for Disease Control and Prevention are sending mixed signals about the virus.

While Obama says you can’t simply catch it from riding on a plane or bus, the CDC at the same time has cautioned people experiencing symptoms to "limit your contact with other people" and "avoid public transportation."

The CDC also advises people who may have been exposed to the Ebola virus to remain in controlled movement, which means, in part, "These individuals should not travel by commercial conveyances (e.g. airplane, ship, long-distance bus, or train)."

CDC director Tom Frieden recently addressed this on a conference call with reporters :

"I think there are two different parts of that equation. The first is, if you're a member of the traveling public and are healthy, should you be worried that you might have gotten it by sitting next to someone? The answer is no. Second, if you're sick, and you may have Ebola, should you get on a bus? The answer to that is also no. You might become ill; you might have a problem that exposes someone around you. Because the risk is so low, we think there is an extremely low likelihood that anyone who travelled on this plane would have been exposed, but we're putting into place extra margins of safety and that's why we're contacting everyone who was on that flight."

Experts told us this appears to be a case of the CDC taking extra precautions to be safe.

"The risk comes from the direct contact with the human secretions and is greatest in the hospital when the secretions are heavily contaminated with lots of viable virus or in an intimate home setting for the person in the earliest stage of illness when no one thinks to take any precautions because it seems like a ‘regular’ illness," Fekete said. "But none of these things describe what happens on bus or plane rides."

Planes, trains and automobiles

So how might someone get Ebola from riding on a bus or train?

Ebola is not airborne. So you would have to be in close proximity to someone who is infected with Ebola and at least has a fever.

On top of that, you would have to come in direct contact with bodily fluids from the infected individual.

The most realistic scenario we could think of is someone sitting next to you is really sick and throws up on you. It’s an upsetting situation, to be sure, and without thinking you touch your nose or your eyes before you’re fully disinfected.

However, people who are sick enough to be vomiting are also very unlikely to be in a state where they can take public transportation or fly, said Anne Rimoin, an epidemiology professor at the UCLA Fielding School of Public Health. That’s why so far the only individuals who have contracted Ebola in the United States have been health care workers.

"The thing about Ebola is that at the point that you’re really infectious to other people is when you are in the later stages of your illness, when you have really terrible diarrhea and nonstop vomiting," Rimoin said. "And nobody is going to be in contact with somebody who has Ebola at that stage under any kind of normal situation."

What about a sneeze or cough? Stephen Gire, a researcher at the Harvard Department of Organismic and Evolutionary Biology who studies the Ebola genome, said if someone who is showing symptoms sneezed directly on you from within 3 feet, it could, technically, transfer the virus. But people further away wouldn’t have to worry about those particles lingering in the air.

We should add coughing and sneezing are not symptoms of Ebola and there’s no documented evidence the disease has ever been transmitted this way.

What if bodily fluids from an infected individual ended up on a bus seat or a plane armrest? Could you get the Ebola virus that way?

Under very limited conditions the virus could survive outside the body, Gire said.

First, the fluid would have to remain in liquid form. Once it dried up, the virus would die. Second, it would have to be a very cool and dark setting.

"It has to be a highly engineered environment for Ebola to survive in this environment," Gire said. "Stable temperature; on the right type of surface; not exposed to light, etc. These are highly, highly unlikely scenarios in nature and normal environments, and should not be seen as something that is likely to happen."

Our ruling

Obama said, "You cannot get (Ebola) from just riding on a plane or a bus."

He’s right in the sense that you can’t get it "just" from being on a plane or bus with someone who is infected. It would take additional steps: The infected person must be showing symptoms and you must have direct contact with that individual’s bodily fluids, i.e. blood or vomit.

Could that happen? Hypothetically, sure. Experts confirmed as much, and the CDC goes so far as to warn people exposed to the virus that they should not take public transportation.

But it’s also a very unlikely scenario. It’s rare that one would ever come in direct contact with bodily fluids from sick people while riding on a bus or plane. And someone in that stage of the disease is likely too sick to fly or ride.

Experts said the probability of such a transmission occurring is so small that the sentiment is largely accurate. We rate the statement Mostly True.