Holiday travel can be safe if you’re fully vaccinated against COVID-19, but officials say people who haven’t gotten the shots should delay travel.

Regardless of vaccination status, all travelers should keep taking precautions like avoiding indoor, unmasked crowds, says Dr. Keith Armitage, an infectious disease expert at Case Western Reserve University.

“The delta variant has really brought us back to an earlier time in the pandemic,” he says.

The U.S. Centers for Disease Control and Prevention says not to travel if you’re sick, or if you tested positive for COVID-19 and your isolation period isn’t over yet — even if you’re fully vaccinated. Unvaccinated people who decide to travel should get a COVID-19 test one to three days before travel and three to five days after returning.

All travelers must still wear masks on trains, planes and other indoor public transportation areas, the agency says.

Airlines say plane cabins are low risk since they have good air circulation and filtration. However, there is no requirement for vaccination or testing before domestic flights, and passengers can remove their face masks while eating or drinking.

Hotels aren’t risky for the vaccinated as long as they wear masks around strangers, Armitage says. More fraught are family gatherings with unvaccinated individuals, particularly for those who are older or have health problems.

Health experts suggest looking at the case levels and masking rules in the place you are visiting before you travel.