The COVID-19 vaccines remain effective in preventing serious disease, hospitalization, and death from the SARS-CoV-2 virus. Unvaccinated persons are more likely to get infected and spread the virus which is transmitted through the air and concentrates indoors. To ensure that we collectively protect the health and well-being of all Californians; keep schools open for in-person instruction; and allow California’s economy to remain open and thrive, the California Department of Public Health (CDPH) is requiring masks to be worn in all indoor public settings, irrespective of vaccine status, for the next four weeks (December 15, 2021, through January 15, 2022).