Health officials in Los Angeles County, the nation's largest, are blaming increasing transmission of COVID-19.
RELATED: LA County reinstating indoor mask mandate regardless of COVID vaccination status
Dr. Muntu Davis, the county's Public Health officer said, "Waiting for us to be at a high community transmission level before making a change would be too late."
Across much of the country, the spike in new Coronavirus cases is fueled by the Delta variant. The CDC reported cases are on the rise in at least 45 states, with the U.S. back to an average of 1,000 new cases reported every hour.
"Unvaccinated people are driving this pandemic for us," Dr. Yvonne Maldonado told ABC7 News.
Dr. Maldonado is an infectious disease expert with Stanford Health, School of Medicine. She said even vaccinated people are going to have about a 5% risk of infection.
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She warned, those who are vaccinated should feel comfortable, yet remain cautious.
"It's not 100%," Dr. Maldonado said. "It's pretty close to 100% effective, but even a small percentage of a lot of people can be a lot of people."
In the Bay Area, Alameda and Marin County public health officials told ABC7 News they're considering specifically recommending masking indoors for everyone.
RELATED: Will Delta variant bring new CA restrictions? Newsom weighs in
Alameda County explained, "While vaccination continues to be the best protection against severe COVID-19 infection, we are considering recommending masking indoors for everyone because it is a powerful tool that can help contain this more transmissible virus."
"We have not yet changed any recommendations, but given the increased COVID-19 case rates, including breakthrough cases, we are closely monitoring our data and considering it as an option if the data warrants," Marin County shared.
San Mateo County said, "Our health officers are looking at case rate, hospitalization and death data and are considering if any changes in current recommendations might be helpful."
Other health departments told ABC7 News they are planning to stick with state guidelines, which do not require indoor masking for vaccinated people.
RELATED: Doctors investigate rare COVID breakthrough cases infecting vaccinated Californians
"I do think that in certain situations, it might be helpful to suggest indoor masking," Dr. Maldonado said. "I'm not sure about a mask mandate. We're not there yet."
ABC7 News reporter Amanda del Castillo took the question to Twitter, asking if vaccinated people would continue with or without masks.
In just a few hours, more than 240 people answered the poll.
#POLL: LA County is REINSTATING it’s indoor mask mandate, regardless of #COVID vaccination status.— Amanda del Castillo (@AmandaABC7) July 15, 2021
Reason: rapid + sustained increase in COVID cases. #QUESTION: What action will you take?
Story: https://t.co/yvVJ28U5QR #abc7now
Dr. Maldonado encouraged, "Let's just see what happens in the next week or so. Remember in May, this virus only represented 6% of the strains, and right now it's at around 70%."
"So it's moving very quickly," she added.
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