Some major hospitals, aware of the inadequacy of the older C.D.C. guidelines, have followed more stringent standards in training their staff. But many — including Texas Health Presbyterian Hospital in Dallas, where two nurses were infected by a dying patient — have not.

The Doctors Without Borders guidelines are even stricter than the new C.D.C. directives in that they require full coverage of the torso, head and legs with fabrics that blood or vomit cannot soak through, along with rubber aprons, goggles or face shields, sealed wrists and rubber boots. Doctors and nurses wear two sets of gloves, including long outer ones that strap or are taped to the gown; janitors wear three sets.

As they undress in choreographed steps, Doctors Without Borders workers wash their hands with chlorine solution eight times and are sprayed with a chlorine mist. Most important, all personnel disrobe only under the eyes of a supervisor whose job is to prevent even a single misstep.

Risky procedures like blood sampling are kept to a minimum.

“I’ve seen the C.D.C. poster,” said a Doctors Without Borders representative who spoke on the condition of anonymity because she did not want to be named criticizing the agency, and who was referring to C.D.C. guidelines before they were changed on Tuesday. “It doesn’t say anywhere that it’s for Ebola. I was surprised that it was only one set of gloves, and the rest bare hands. It seems to be for general cases of infectious disease.”

National Nurses United, the country’s largest union and professional association of nurses, with 185,000 members, criticized the C.D.C. on Wednesday for taking so long. Worse, the union said, many hospitals ignored even the lax guidelines because they were voluntary.

For example, the union said, nurses at the Texas hospital complained that the protective gear the hospital issued left their necks exposed — and they were told to wrap their necks with medical tape.