1 of 5 | Passengers are seen in the departure hall next to a sign promoting travel to New York City, at Ben Gurion International Airport near Tel Aviv, Israel, on September 22. International travelers entering the U.S. must abide by new testing rules that took effect Monday. File Photo by Debbie Hill/UPI | License Photo
Dec. 6 (UPI) -- New travel restrictions took effect on Monday for foreign travelers entering the United States, due to concern about their potential to spread the Omicron coronavirus variant.
The Centers for Disease Control and Prevention tightened testing rules for international travelers amid rising COVID-19 cases in the United States, regardless of vaccination status.
The CDC shortened the time frame that foreign travelers must obtain a negative test before U.S. travel, from three days to one.
The agency says the changes are intended to prevent "further introduction, transmission and spread" of COVID-19, including the Omicron mutation and "other new virus variants."
The only international U.S.-bound travelers who will be exempt from the shorter testing requirement are those who can prove that they have recovered from COVID-19 in the past 90 days, officials said.
The new restriction is part of a series of changes by President Joe Biden's administration last week intended to mitigate the threat of the Omicron variant, which scientists are still trying to understand. Biden has also extended a mask mandate for commercial flights, trains, buses and at airports until mid-March. It was previously set to expire in January.
Meanwhile, coronavirus cases in the United States are beginning to tick back up.
Over the weekend, the daily average for new COVID-19 cases nationwide surpassed 100,000 for the first time in two months, according to Johns Hopkins University.
The seven-day average rose to more than 120,000 on Saturday after remaining below 100,000 since October.
The Omicron variant has been identified in more than a dozen states so far. Health officials have said, however, that the Delta variant remains the dominant virus variant in the United States.
U.S. Surgeon General Dr. Vivek Murthy said last week that researchers are prepared to fight the new variant and slow the spread.
"We are in such a different place now than we were one year ago because we've learned a lot more, Murthy told CNN.
"We have vaccines available. We have far more tests available, and what we've got to do to get through this winter is to make sure that we are doubling down on our vaccination strategy."
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and Biden's chief medical adviser, said on Sunday that preliminary data about the Omicron variant is "encouraging" in that it may not be as dangerous as initially feared.
"We have really got to be careful before we make any determinations that it is less severe, or really doesn't cause any severe illness comparable to Delta," he told CNN. "But thus far, the signals are a bit encouraging regarding the severity."