LOS ANGELES — Los Angeles County residents are again required to wear masks indoors regardless of their vaccination status — a new mandate starting this weekend that health officials hope will reverse the latest spikes in coronavirus cases, hospitalizations and deaths.

The rule went into effect late Saturday for the nation’s largest county, home to 11 million people, where a sharp increase in COVID-19 cases is led by the highly transmissible delta variant.

The vast majority of new cases are among unvaccinated people, LA County Supervisor Hilda Solis said Sunday.

“I’m not pleased that we have to go back to using the masks in this matter but, nonetheless, it’s going to save lives. And right now that to me is what’s most important,” Solis said on ABC’s “ This Week.”

California has seen a steady rise in virus cases since the state fully reopened its economy on June 15 and did away with capacity limits and social distancing.

San Francisco Bay Area health officials last week urged residents to again wear masks inside public buildings regardless of whether they are vaccinated. The counties of San Francisco, Santa Clara, San Mateo, Marin, Alameda, Contra Costa and Sonoma and the city of Berkeley stopped short of making face coverings mandatory.

Other counties, including Sacramento and Yolo, are also strongly urging people to wear masks indoors.

Los Angeles County reported a caseload of 1,635 on Sunday — the 10th straight day with more than a thousand new cases. On June 15, when the state reopened, county health officials reported just 210 new cases.