It may not be time to pop the prosecco just yet, but a trip to Rome without a required quarantine may be available sooner than anyone expected. Quarantine-free trips to Amsterdam and London are taking off, too, as airlines experiment with creating safe-travel corridors, fortified by passenger testing for COVID-19.

Delta Air Lines will begin trial flights between Atlanta and Amsterdam on Dec. 15 and between Atlanta and Rome on Dec. 19.

Delta and its partner KLM Royal Dutch Airlines are launching the Atlanta-Amsterdam COVID-tested flights to allow passengers to forgo the usual 10-day quarantine in the Netherlands. Passengers on the four designated weekly flights must test negative for COVID-19 with a polymerase chain reaction test five days before arrival in Amsterdam and self-isolate after the test. They will also take a rapid antigen test before boarding in Atlanta and take another PCR test upon arrival in Amsterdam. With a negative result from that last test, their quarantine requirement will be lifted.

Fliers can choose the COVID-tested flights or take one of the other daily flights between Atlanta and Amsterdam.

If the three-week trial is deemed successful, the airlines hope to extend the program to other markets.

Protocols are slightly different for the flights between Atlanta and Rome. Passengers will be exempt from a 14-day quarantine upon arrival in Italy, provided they test negative for COVID-19 three times: 72 hours before departure, before boarding in Atlanta and upon arrival in Rome. The first test, at fliers’ expense, must be a polymerase chain reaction test, which is commonly available and checks for the virus’ genetic material. The pre- and post-flight tests will be rapid antigen tests, and costs will be covered by Delta.

One caveat: The quarantine exemption on both routes are available for U.S. citizens traveling to Italy or the Netherlands for essential reasons, such as for work, health and education.

Meanwhile, both American and United Airlines have begun trial programs on flights to London.

American Airlines and its partner British Airways have started testing volunteers on flights to London from Dallas, New York and Los Angeles. The optional testing — three days ahead of the flight, at the airport and three days after arrival in London — is covered by the airlines. “The ultimate objective of this and other trials is to validate that a pre-departure test provides a high level of certainty of a passenger being COVID-19 negative, which [is] hoped to result in policies that further relax U.S. and U.K. border restrictions,” according to a statement by the airline.

Travelers to the United Kingdom, whether they’re participating in the program or not, currently need to quarantine for 14 days. On Dec. 15, new rules for England take effect. Travelers who test negative for the coronavirus on day five or thereafter will no longer need to finish the 14 days. (Scotland, Wales and Northern Ireland have not yet changed their quarantine rules.)

United Airlines began its four-week trial program on Nov. 16. On select flights between Newark and London, each traveler over the age of 2 is required to take a free rapid COVID-19 test before boarding.