LOS ANGELES (AP) — 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, offices or businesses 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 a requirement. 

Other counties, including Sacramento and Yolo, are also strongly urging people to wear masks indoors but not requiring it.

Los Angeles County's mask rule, announced Thursday, follows a winter where the region experienced a massive surge in infections and deaths, with hospitals overloaded with COVID-19 patients and ambulances idling outside, waiting for beds to open.

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.

More than 525 people were hospitalized with COVID-19 in LA County on Saturday, the highest number since April 14. There were four new virus-related deaths reported Sunday.

“The level of COVID-19 transmission we are currently experiencing is now leading to significant increases in serious illness and hospitalizations, and requires us to take immediate action to prevent erosion of our recovery efforts," Barbara Ferrer, the county's public health director, said in a statement.

LA County Supervisor Kathryn Barger came out in opposition to the new mask mandate, saying by deviating from the state rules “we create confusion and disagreement at the local level, which hinders public trust.”

Sheriff Alex Villanueva said Friday his deputies will not actively enforce the mandate, saying requiring vaccinated people to wear masks “is not backed by science and contradicts the U.S. Centers for Disease Control and Prevention guidelines.”

Solis said that the LA County mask rule is “not punishment, it’s prevention.” But some vaccinated residents said it felt like they were being penalized despite doing the right thing.