A social distancing sign on a seat in the check-in area in at London Heathrow Airport Ltd. in London, U.K., on Saturday, Dec. 19, 2020. The pandemic has put a third of all tourism jobs at risk, and airlines around the world have said they need as much as $200 billion in bailouts.

Source: Eric Quintanar

The Trump administration enacted new travel restrictions this week that, effective Monday, will curb the number of travelers entering the U.S. from Britain in an effort to prevent the spread of a coronavirus strain health authorities believe is more contagious.

The federal government’s new travel guidelines, designed to prevent the spread of a COVID-19 strain identified in the U.K., will require travelers entering the U.S. from Britain to test negative for COVID-19 within 72 hours of their planned departure.

“Viruses constantly change through mutation, and preliminary analysis in the U.K. suggests that this new variant may be up to 70% more transmissible than previously circulating variants,” said the Centers for Disease Control and Prevention in a statement on Thursday.

Although some airlines have already instituted similar policies, such as for those traveling from London to New York, all airlines will now be forced to verify that passengers have tested negative within the required timeframe when entering any part of the U.S., reports AP. Travelers who refuse to provide proof of a negative COVID-19 test from the last 72 hours must be denied boarding.

“This new order is consistent with the measures that have been taken so far to increase our ability to detect and contain COVID-19 proactively and aggressively,” said the CDC.

Vaccine scientists believe that existing COVID-19 vaccines will still be effective against the new SARS-CoV-2 strain.

“I don’t think there has been a single variant that would be resistant to the virus — to the vaccine,” Dr. Moncef Slaoui, a top doctor for Operation Warp Speed, told CNN last week. “We can’t exclude it, but it’s not there now. And this particular variant in the U.K., I think, is very unlikely to have escaped the vaccine immunity.”

But with vaccine distribution still in its infancy, the arrival of a more contagious strain could give the virus a chance to spread even more before COVID-19 vaccines become widely available. (Currently, the U.S. says it will have enough COVID-19 vaccines for 200 million Americans to receive a two-dose regimen by the end of July 2021.)

The new SARS-CoV-2 strain has already been identified in cases in other countries, including France, Spain, and Canada. On Friday, Japanese health authorities identified the strain in people arriving to the country via airplane, and also recently found the strain in a man who recently visited the U.K., according to Reuters.

In New York City, Mayor Bill de Blasio has announced a policy wherein every traveler from the U.K. will receive a personal visit from a sheriff’s deputy reminding them to following quarantine orders. If they refuse to quarantine, said the New York City mayor, “they will be penalized. We cannot take chances with anyone who travels, particularly folks traveling in from the U.K.”

The penalty for breaking the quarantine order is $1,000, plus an additional $1,000 fine for each extra day a person spends violating the order.