New guidelines for the personal protective equipment that health workers should have on when treating Ebola patients make clear that what you wear counts — but even more important is how you put it on and take it off.

And the guidelines that the World Health Organization updated Friday suggest only highly trained medical professionals should be taking on the dangerous job of caring for Ebola patients, say the country’s leading doctors at the National Institutes of Health.

“Anybody could do this, but the training process is something that takes a lot of time,” Dr. Francis Collins, who heads the National Institutes of Health, told NBC News in an interview.

Treating Ebola patients does not have to be dangerous, Collins said. “But it takes a lot of time to make it safe.”

That was obvious in a demonstration given this week at the NIH clinical center, where Dallas nurse Nina Pham was cared for until she was released earlier this month. It took a full 10 minutes to gear up Kevin Barrett, a specialist nurse who helped care for Pham.

“One of the most dangerous times is when someone is doffing or taking off their gear."

“First Kevin, please don the belt,” says Dr. Tara Palmore, hospital epidemiologist for the NIH Clinical Center. She’s spotting Barrett. Ebola veterans say having someone watch you put on — and, more importantly, take off — Ebola gear can make the difference between safely treating a patient and getting infected yourself.

“Then don the shoe covers,” Palmore adds, reading from a checklist. Barrett systematically puts on a white Tyvek full-body suit, two pairs of shoe covers, a helmet called a powered air purifying respirator (PAPR or “papper” for short), a “shroud” over his PAPR and head, a two-way radio that’s hooked to his belt, two pairs of gloves, taped on using a special trick so the tape can be pulled off easily later, and a yellow gown.

Doffing the gear takes even longer. “One of the most dangerous times is when someone is doffing or taking off their gear,” said Dr. Anthony Fauci, head of the NIH’s National Institute for Allergy and Infectious Diseases.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Palmore spots Barrett every step of the way, instructing him step by step. In a real patient care situation, she’d be suited up too, just in case something splashed off onto her.

The goal is to get all these layers off without ripping them and without carrying any possible contamination outside the room where the patient is. Experience led to the trick with the tape, said Fauci — just folding the end over itself leaves a non-sticky length that can be pulled without ripping the sleeve of the suit.

That’s one of the flaws that Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, saw at the Texas Health Presbyterian hospital in Dallas, where Pham and her fellow nurse Amber Vinson became infected. They layered on too many pairs of gloves and rolled on so much tape they had trouble getting the gear off safely.

The CDC released its own instructional video Friday.

Health care workers often get infected even while wearing personal protective equipment, or PPE. Hundreds have become infected and have died at the front lines in Liberia, Sierra Leone and Guinea, and Pham and Vinson were infected while taking care of Thomas Eric Duncan, the only person so far to die of Ebola in the United States.

Most experts think infection was due to a gear malfunction of some type — perhaps a small mistake made when taking off contaminated PPE.

The new WHO guidelines don’t specify any particular piece of equipment. They make clear what needs to be protected — and in treating Ebola, that is every part of the body, from the top of the head to the bottom of the feet.

Ebola isn’t as contagious as influenza, measles or even the common cold. It doesn’t float in the air or live on surfaces. To get it, people have to be in close contact with someone who is actively sick or with the person's bodily fluids, such as on a sheet covered with vomit or diarrhea. But doctors, nurses and technicians fall squarely into this risk group.

The WHO guidelines emphasize that PPE must keep virus out of the eyes, nose and mouth, as well as off the hands. It’s also important to keep it off any part of the body that someone might touch later, because the hands can carry it to eyes, nose and mouth. That's why skin must be covered — not because the virus can infect through the skin, but because you might touch it later.

“Paramount to the guidelines’ effectiveness is the inclusion of mandatory training on the putting on, taking off and decontaminating of PPE, followed by mentoring for all users before engaging in any clinical care,” said Edward Kelley, WHO’s director for service delivery and safety.

It might seem like you can never have too many layers, but the gear is hot and hard to move around in.

"I would say categorically that unless you have rehearsed, you should not do it."

And a hot, tired worker makes mistakes. “This process is not an easy process, and you are the most fatigued when you are taking off your material,” Fauci said. “That’s a time when you are very vulnerable.”

Fauci agrees with Collins — caring for Ebola patients is not work for amateurs. “I would say categorically that unless you have rehearsed, you should not do it,” Fauci told NBC News.

In July, Frieden said any U.S. hospital should be able to care for an Ebola patient. Fauci disagrees. “You don’t expect every single hospital in the country to be able to fully take care of an Ebola patient, but you expect the clinics and emergency rooms to be able to recognize when an Ebola patient comes through the door or is carried through the door,” Fauci said. The right thing to do is then get the patient to an appropriate facility, where staff have rehearsed how to safely care for such a patient.

“When the outbreak came we were well-trained and suited to do this,” Fauci said. The NIH clinical center, Emory University Hospital and the Nebraska Medical Center all have special biocontainment units where staff are trained to care for patients with dangerous illnesses.

Bellevue Hospital in New York is caring for Dr. Craig Spencer, a doctor infected in Guinea while treating Ebola patients. Bellevue is one of dozens of hospitals that have drilled recently in the care of such patients.