The Centers for Disease Control and Prevention updated its travel guidelines on Friday to say people who are fully vaccinated for COVID-19 can safely travel in the United States and overseas without self-quarantine or a coronavirus test, as long as they wear a mask in public spaces.

This guidance does not change the guidelines for unvaccinated individuals. 

Recent studies evaluating the real-world effectiveness of the COVID-19 vaccines prove that vaccinated people can travel at a low risk to themselves, according to the agency. A person is fully vaccinated at least two weeks after receiving their last recommended dose of the vaccine.

The CDC guidance says it is safe for fully vaccinated individuals to travel both domestically and internationally as long as they take mitigation measures such as wearing a mask, washing hands and avoiding crowds.

But when traveling internationally, fully vaccinated people should still have a negative COVID-19 test before boarding a flight back to the U.S. and another negative test three to five days after returning from international travel, according to CDC.

The CDC’s new travel rules do not change existing guidance for people who are not fully vaccinated. Unvaccinated individuals who must travel should still get tested one to three days before domestic travel and again three to five days after travel. Unvaccinated travelers should also self-quarantine for seven-to-10 days after travel. The CDC does not recommend travel for unvaccinated individuals.

“With millions of Americans getting vaccinated every day, it is important to update the public on the latest science about what fully vaccinated people can do safely, now including guidance on safe travel,” CDC Director Rochelle Walensky said in a statement. 

These guidelines will continue to evolve as more and more Americans get vaccinated against COVID-19. As of Friday, 21.7 percent of the adult U.S. population was fully vaccinated against the virus. Many states are opening vaccine eligibility to all adults in the coming weeks as Pfizer, Moderna and Johnson & Johnson are expected to deliver more vaccine doses soon.