United Airlines will require all flyers coming from the United Kingdom to test negative for COVID-19 before their trip, the carrier announced Thursday.

Beginning Monday, passengers over the age of 5 originating in the UK will have to receive a negative test results within 72 hours before departure, the company said in a statement.

United operates flights out of Heathrow to Chicago, Washington Dulles, San Francisco and Newark, New Jersey. The requirement does not apply to passengers with layovers at Heathrow who do not exit the airport.

United joins British Airways, Delta Airlines and Virgin Atlantic in requiring negative tests for UK flyers as that country grapples with a highly contagious new coronavirus mutation that has shut down London.

New Jersey Gov. Phil Murphy on Monday echoed concerns expressed by his New York counterpart Gov. Andrew Cuomo the previous day that flights from the UK could accelerate the spread of COVID-19 in the region.

Both New York and New Jersey advise out-of-state travelers to quarantine for up to 14 days after arrival.

“As we continue to experience a second wave of COVID-19 cases, it’s critical that we take any and all precautions to mitigate the potential for further transmission,” Murphy said in a statement Thursday announcing United’s new policy.

“While New Jersey continues to strongly discourage all non-essential travel at this time, if unavoidable, international travelers should adhere to CDC guidance for pre- and post-flight testing and the recommended self-quarantine period.”