Fully Vaccinated Can Now Go Without Masks In Greeley Greeley is the latest city to announce that it'll be following the guidance of both the CDC and the State of Colorado on mask use. According to an official news release from the City of Greeley, those who are fully vaccinated can now go without masks indoors. "Effective immediately, City of Greeley facilities will follow the updated guidance from the Centers for Disease Control and Prevention and the State of Colorado on mask use, allowing fully vaccinated individuals to go without masks in public indoor spaces unless the setting requires otherwise."