Alameda County December 9, 2022 11:26 am Alameda County Moves to COVID Yellow Tier; Masks Required in Some Settings Alameda County on Thursday moved into the CDC’s yellow tier for COVID-19, meaning masks would be required again in certain high-risk settings, the county said. US & World Videos 4:02 Updated COVID vaccines coming 3:17 Slight summer uptick of COVID cases in California 3:57 Interview: Doctor's perspective on COVID 4 years after shutdown started 2:09 CDC updates COVID isolation guidelines 1:37 Study examines effectiveness of main COVID treatment Paxlovid