Fully vaccinated people can resume recreational travel in the U.S. yet should still wear a mask and avoid crowds, according to new advice from the Centers for Disease Control and Prevention.

The CDC released its long-awaited travel guidance on Friday amid the accelerating pace of vaccinations in the U.S., even as more contagious variants threaten to ignite a new wave of COVID-19 cases and as millions of Americans hit the skies anyhow.

The guidance says that fully vaccinated people don’t need a test, and don’t need to quarantine, when traveling domestically. For international travel, they don’t need a test unless it’s required by their destination country and don’t need to quarantine once back in the U.S., but should get tested before boarding their return flight.

The head of the CDC held out the promise of travel in asking people to get vaccinated when they can. “Vaccines can help us return to the things we love about life, so we encourage every American to get vaccinated as soon as they have the opportunity,” CDC Director Rochelle Walensky said.

All people, even if vaccinated, should still wear masks on planes, the CDC said. The agency considers someone fully vaccinated two weeks after their final shot.

The CDC previously released guidance for what vaccinated people can do. It said fully vaccinated people can gather privately together without masks, or visit one unvaccinated household — such as vaccinated grandparents visiting the home of a child and grandchildren. However, it urged vaccinated Americans to keep wearing masks in public and to avoid crowds. At the time, the CDC didn’t change its travel recommendations.

The CDC still discourages “nonessential domestic travel” by those who aren’t fully vaccinated. Those people should still get tested one to three days before travel, and again three to five days afterward. They should stay home and quarantine for seven days after traveling, or 10 days if they don’t get a test, the CDC says.

U.S. air travel has begun rebounding — 1.6 million people passed through TSA checkpoints Thursday, well above the 124,000 who did so a year before yet still below the 2.4 million from the same day in 2019.

COVID-19 cases have started rising again in the U.S., with 79,000 new cases recorded Thursday. Walensky warned this week that Americans can’t abandon mitigation efforts, saying she is scared of “impending doom” as a fourth wave begins to crest. More than 553,000 people have died of the virus in the U.S., amid more than 30 million cases.