SAN FRANCISCO (KRON) — Seven Bay Area counties are requiring everyone to wear face masks indoors, regardless of vaccination status.

The order is in effect starting Tuesday, August 3.

Health officers representing the counties of Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara and Sonoma made the joint announcement on Monday afternoon.

It’s a “short-term, evidence-based strategy,” to reduce transmission of the delta variant and help keep schools open, said Marin County’s deputy health officer, Dr. Lisa Santora.

The state of California began allowing fully vaccinated people to remove masks in public spaces in June. Since the grand reopening, the COVID-19 delta variant has caused growing concern to health officials who have been recording increased cases and hospitalizations.

Health officials confirmed that the delta variant is “substantially more transmissible than previous forms of the virus.”

Bay Area officials said the delta variant is infecting a “small percentage” of vaccinated Bay Area residents but they are still strongly protected against severe illness, hospitalization and death.

“We know that face coverings work to prevent the circulation of the virus, and with contagious variants spreading it has become clear that mask wearing is again necessary,” said Sonoma County Health Officer Dr. Sundari Mase. “Masking and vaccinations are the most important tools we have to end the pandemic. The vaccine is safe, effective, free and widely available. We encourage all residents to do their part in wearing their masks to keep themselves, their families and their community safe.”

On Saturday, the state’s health department officially reversed course and began recommending indoor mask-wearing, regardless of vaccination status.

Before that, the federal government had also began recommending that people wear masks in virus hot spots.

Last week, San Mateo County was the first in the Bay Area to require masks indoors again for all, but only in county facilities.

“As San Mateo County joins its neighbors in issuing these orders, the goal is to avoid disrupting businesses and residents’ everyday activities,” said Scott Morrow, MD, San Mateo County’s health officer during Monday’s announcement. “We want our communities to stay open while being as safe as possible.”

Businesses in these seven Bay Area counties will be required to implement the indoor face mask order.

Health officials also suggest that people socialize with outdoor activities.

Statewide, California health officials reported increases in COVID trends across the board on Monday.

New cases per 100K increased by an average of 16.7, new deaths per 100K increased by 0.03, and 6.7% of all COVID tests taken came back positive, the California Department of Health reports.

Over 44 million vaccines have been administered in California.