The CDC says people who are fully vaccinated do not need to wear a mask when they're outdoors, unless they're in a crowd, such as attending a live performance, sporting event or parade. … As part of the new guidance, the agency spelled out settings in which it's OK for fully vaccinated people to be unmasked including: walking, running, hiking or biking outdoors alone or with members of your household; attending a small outdoor gathering with fully vaccinated family and friends; attending a small outdoor gathering with a mixture of fully vaccinated and unvaccinated people; dining at an outdoor restaurant with friends from multiple households.