Faced with rising coronavirus cases and growing concerns about the Omicron variant, California is ordering a statewide mask mandate for indoor public spaces to go into effect on Wednesday.

The move comes as coronavirus case rates in California have risen by almost 50% in the last 2½ weeks, and COVID-19 hospitalizations are up by nearly 15%. County health officials across the state say they suspect they may be seeing the start of a winter jump in coronavirus cases.

The U.S. Centers for Disease Control and Prevention ranks California as having a high level of transmission of the coronavirus, the worst tier in the federal agency’s four-tier scale.

“This is a critical time where we have a tool that we know has worked and can work,” Dr. Mark Ghaly, California’s health and human services secretary, said Monday. “We are proactively putting this tool of universal indoor masking in public settings in place to ensure we get through a time of joy and hope — without a darker cloud of concern and despair.”