Anyone flying into the United States from the United Kingdom will have to test negative for COVID-19 within 72 hours before their flight, the Centers for Disease Control and Prevention announced Thursday. The agency cited concerns over a new variant of the coronavirus as the reason for the rule, which goes into effect Monday.

The coronavirus, like all viruses, has regularly mutated as it has spread through the population. Most mutations don’t make a virus behave any differently, but this new variant, which emerged in the UK, does appear to spread more easily than other forms of the virus. It does not appear to make people sicker and does not seem to be more deadly, although researchers are still studying that question. Experts say the already authorized COVID-19 vaccines will likely still be effective against it.

The new variant is spreading quickly through London and southeast England. Prime Minister Boris Johnson put the area under stricter lockdown to contain it, and dozens of countries have banned travelers from the UK.

Two US states, New York and Washington, already have UK travel restrictions in place. British Airways, Delta Air Lines and Virgin Atlantic agreed to New York Governor Andrew Cuomo’s request to test travelers flying into the state. Washington is asking people traveling from the UK to quarantine for 14 days.

Anthony Fauci said on Good Morning America earlier this week that he wouldn’t recommend a full ban on travel from the UK, which he called “draconian.” Testing was a more realistic step, said Fauci, the director of the National Institute of Allergy and Infectious Diseases.

Asking travelers to get COVID-19 tests is a more effective screen than temperature and symptom checks, which don’t end up catching many sick people. Still, a test within three days of traveling won’t be a perfect net: someone could test negative a day before their trip and develop symptoms when they land.

It’s possible that the new variant is already circulating in the US, Fauci said. “When you have this amount of spread within a place like the UK, you really need to assume that it’s here already.”

https://www.theverge.com/2020/12/25/22199682/covid-test-uk-travelers-us-cdc-virus-mutation