Los Angeles County will once again require masks be worn indoors, even by those fully vaccinated against COVID-19, due to a recent surge in cases, according to ABC News.

The University of California system has also said that students, faculty and staff must be vaccinated against COVID-19 to return to campuses.

The announcements have come after a recent spike in cases, with many of them carrying the highly contagious Delta variant – the strain that was first detected in India.

Dr. Muntu Davis, Public Health Officer for Los Angeles County, said the rapid and sustained increase in cases requires restoring an indoor mask mandate that will go into effect just before midnight Saturday.

He said in a virtual news conference, “This is an all-hands-on-deck moment,” adding that authorities will focus on education rather than enforcement.

The nation’s largest county has been recording over 1,000 new cases per day for a week, and there is now “substantial community transmission,” Dr. Davis said. “The next level is high transmission, and that’s not a place where we want to be.”

Meanwhile, other counties, including Yolo and Sacramento, are strongly urging people to wear masks indoors.

Dr. Olivia Kasirye, Sacramento County Public Health Officer, said, “The drastic increase in cases is concerning — as is the number of people choosing not to get vaccinated.”

Dr. Michael Drake, President of the University of California, said unvaccinated students without approved exemptions will be barred from in-person classes, events, and campus facilities.

“Vaccination is by far the most effective way to prevent severe disease and death after exposure to the virus and to reduce spread of the disease to those who are not able, or not yet eligible, to receive the vaccine,” Dr. Drake wrote in a letter to the system’s 10 chancellors.

In San Francisco, officials have reported a surge in cases among the unvaccinated, with Black and Latino people getting shots at a much lower rate than others. San Francisco Mayor London Breed has urged them to get the vaccine.

Vaccines have been found effective in decreasing the severity of the illness and reducing hospitalizations as well as the risk of death.

Pfizer and Moderna vaccines have been found 95% effective, while the J&J vaccine has been found 72% effective against COVID-19 in the United States.

The Food and Drug Administration (FDA) analyzed the vaccines and cautioned that it is not clear how well they work against each variant. It also said that “breakthrough” cases among the fully vaccinated are rare. The article was published on ABC News.