The waiver, backed by rigorous testing before departure and on arrival, is the first on a trans-Atlantic route, according to Delta Air Lines Inc., whose flights from Atlanta to Rome Fiumicino will trial the new rules. Alitalia will serve the Italian capital from New York John F. Kennedy airport on the same basis.

The International Air Transport Association told Bloomberg that it knows of no other quarantine-exempt services from the U.S. to Europe.

While marking a further advance toward reopening the lucrative North Atlantic market, significant restrictions remain. The policy applies in only one direction, with the U.S. maintaining an effective bar on non-nationals entering the country, and Americans must have “essential reasons” for visiting Italy.

Delta will introduce the flights from Dec. 19, it said in a statement Thursday, adding that reasonable grounds for travel include work, health, and education.

Italy, hit hard by the pandemic, has been experimenting for weeks with COVID testing on flights between Rome and Milan, as well as to Germany. Getting buy-in from the U.S. and other European countries is key to the airline industry’s push to replace the system of restrictions, including quarantines, that has deprived them of North Atlantic revenue.

Italy currently imposes a 14-day quarantine on arriving travelers from the U.S. EU arrivals are broken into groups with varying restrictions based on infection levels in the country of departure.

Since March, the U.S. has suspended entry to most travelers from the EU, while American citizens are free to enter. Several domestic agencies have recommended that the Trump administration lift the ban, people briefed on the discussions said Wednesday.

Other trans-Atlantic flights aimed at trialing COVID testing don’t feature quarantine waivers, such as services to London operated by British Airways and American Airlines Group Inc. from Dallas, New York, and Los Angeles, and by United Airlines from Newark.