Customs and Border Protection officers at New York's Kennedy, Newark Liberty, Washington's Dulles, Chicago's O'Hare and Hartsfield-Jackson Atlanta airports had already started screening people arriving from West Africa, using no-touch thermometers to determine if travellers have a temperature, a symptom of a possible Ebola infection.
Homeland Security Secretary Jeh Johnson said Tuesday that now everyone travelling from Liberia, Sierra Leone or Guinea will have to land in the U.S. at one of the five airports and then fly on to their destination.
About 94 per cent of the roughly 150 people travelling daily from West Africa to the U.S. arrive at the one of the five airports.
The move falls short of meeting demands by some elected officials that the Obama administration halt all travel from West Africa. Sen. Chuck Schumer, D-N.Y., described the action as an "added layer of protection against Ebola entering our country."
It comes as the Centers for Disease Control worked to spread the word about its new protective guidelines. The, advice, released Monday night, had been avidly sought by health workers after two Dallas nurses became infected while caring for the first person diagnosed with the virus in the United States.
It's not clear exactly how they became infected, but clearly there was some kind of problem, CDC Director Dr. Tom Frieden said.
"The bottom line is the guidelines didn't work for that hospital," he said.
CDC officials demonstrated the recommended techniques Tuesday at a massive training at New York City's Javits Center.
"We're here today because one health care worker getting Ebola while caring for a patient is too many," Dr. Arjun Srinivasan told the gathering.
Earlier CDC guidelines had been modeled on how Ebola patients in Africa were treated, though that tends to be less intensive care done in rougher settings — like tents. They also allowed hospitals some flexibility to use available covering when dealing with suspected Ebola patients.
The new guidelines set a firmer standard, calling for full-body garb and hoods that protect worker's necks; setting rigorous rules for removal of equipment and disinfection of hands; and calling for a "site manager" to supervise the putting on and taking off of equipment.
They also call for health workers who may be involved in an Ebola patient's care to repeatedly practice and demonstrate proficiency in donning and doffing gear — before ever being allowed near a patient.
And they ask hospitals to establish designated areas for putting on and taking off equipment, whether it's a room adjacent to an Ebola patient's room or a hallway area cordoned off with a plastic sheet.
The CDC cannot require hospitals to follow the guidance; it's merely official advice. But these are the rules hospitals are following as they face the possibility of encountering patients with a deadly infectious disease that a few months ago had never been seen in this country.
The president of a group representing 3 million registered nurses said she's glad to finally see better federal advice. Health care workers said the CDC's old guidance was confusing and inadequate, and left them fearfully unprepared for how to deal with an Ebola patient.
"Today's guidance moves us forward," said Pamela Cipriano, president of the American Nurses Association, in a statement.
Schmall reported from Dallas. Alicia A. Caldwell reported from Washington.