The carrier has “made great progress to achieve herd immunity,” a trajectory it wants to maintain with the new standard, Delta said Friday. Vaccination isn’t required for current workers, though more than 60% of its workforce has received shots.

“This is an important move to protect our people and our customers, ensuring we can safely operate as demand returns,” the airline said.

The announcement came a day after the Centers for Disease Control and Prevention said that fully vaccinated Americans should be able to stop wearing face masks in most settings, a turning point in the fight against COVID-19. All travelers, vaccinated ones as well, are still required to wear masks on airplanes and in airports under federal rules.

Looser restrictions and increased vaccination rates across the country are prompting people to get back on planes. Travel through U.S. airports was minimal at this time last year but today is about 65% of where it was during the equivalent period in 2019.

Delta’s change takes effect May 17 and allows exceptions, such as for medical conditions. Employees who aren’t vaccinated can be restricted from international flights if shots are required by other countries. The Atlanta-based company has made vaccinations available to all its employees.

American Airlines Group Inc. isn’t requiring employees to be vaccinated, although it is offering an additional vacation day next year and a $50 gift card to encourage people to get shots.

United Airlines Holdings Inc. said nothing has changed since January, when the carrier said it would like to make employee vaccinations mandatory, but couldn’t without other large companies doing the same. Southwest Airlines Co. and Alaska Air Group Inc. said they don’t plan to require employee vaccinations.

—With assistance from Justin Bachman.