Jan. 26 (UPI) -- Beginning Tuesday, all travelers who enter the United States through any airport nationwide must show that they have recently tested negative for COVID-19.
The Centers for Disease Control and Prevention announced the rule two weeks ago as a measure to tamp down on the spread of the virus through U.S. airports.
Under the new rule, passengers must provide a negative COVID-19 test no more than 72 hours before their flight.
"If you plan to travel internationally, you will need to get tested no more than three days before you travel by air into the United States and show your negative result to the airline before you board your flight," the CDC said in a statement Tuesday.
Passengers can provide a negative result from either a polymerase chain reaction (PCR) or antigen test.
The restriction applies to all travelers, including U.S. citizens.
Passengers who have recovered from COVID-19 must show proof of a recent positive viral test and a letter from a healthcare provider or public health official stating they are cleared to travel, the CDC said.
Many other countries have already been requiring negative tests for travelers, but the United States has been less strict in travel requirements.
The CDC also recommends that travelers are tested three to five days after travel and that they stay home to self-quarantine for seven days after travel.
"Even if you test negative, stay home to self-quarantine for the full 7 days," the agency said.
The new rules have spurred a testing cottage industry in tourist areas in Mexico and the Caribbean, where some Americans have been vacationing due to travel bans to other parts of the world.
In Los Cabos, Mexico, every hotel provides a testing site for visitors.
"We want everyone to be easily tested and it should be affordable because that gives everyone more confidence," Rodrigo Esponda, managing director of the Los Cabos Tourism Board, told The New York Times.
Many U.S. airports are now offering rapid testing and some carriers have been offering free passenger testing since the fall on certain flights.
The Biden administration on Monday dismissed an order by the Trump administration to lift a coronavirus ban on travelers from Britain, Ireland, Brazil and most of Europe. The order would have taken effect Tuesday.