California Governor Gavin Newsom said on Tuesday that the state will require health care workers to get booster shots of COVID-19 vaccines in order to make hospitals safer for the patients.

The state has already imposed a vaccination requirement for the workers, a move that had resulted in multiple suspensions since September this year. New Mexico is the only other state to have imposed a booster shot requirement.

“As the Omicron variant continues to spread — we’re stepping up efforts to get more people boosted and keep Californians safe”, Newsom said in a tweet on Tuesday, which also contained a video message.

Several details of the new booster shot mandate remain unclear. These include how many workers would be affected and whether frequent testing would be allowed as an alternative.

Newsom, a member of the Democratic party, has scheduled a press conference in San Francisco Bay Area on Wednesday.

California has so far fared far better than many other states that are dealing with a coronavirus surge, with areas in the Midwest and Northeast seeing the biggest jump in cases and hospitalisations amid frigid temperatures that have kept people indoors.

The United States Centers for Disease Control and Prevention lists California as a place with “high” transmission of the virus, along with nearly everywhere else in the country. But in the last week California averaged 114 new cases per 100,000 people, less than half the national rate, according to reports from Associated Press.

Meanwhile, coronavirus related hospitalisations have been rising slowly in California, up 15% in the last 11 days to 3,852. That’s less than half as many as during the late summer peak and one-fifth of a year ago, before vaccines were widely available.