Updated COVID-19 Quarantine and Isolation guidance website [cdc.gov] from the U.S. Centers for Disease Control and Prevention January 5, 2022:

These updated recommendations come as the Omicron variant is now rapidly spreading throughout the United States , causing very high case rates. The recommendations reflect the societal impact (e.g., critical infrastructure and staffing shortages) and the latest science on disease severity and when and for how long a person is maximally infectious. 

This guidance applies to the general population in the community, including workplaces and K-12 schools [cdc.gov]; this guidance does not apply to healthcare settings [cdc.gov], correctional institutions [cdc.gov], or homeless shelters [cdc.gov].

To accompany the guidance, CDC has developed a corresponding rationale and FAQs [cdc.gov].