SAN FRANCISCO (KGO) -- Bay Area doctors and health officials are concerned about the rapid spread of the COVID-19 Delta variant, warning significant outbreaks could trigger a setback for the state.
This comes one day after the World Health Organization released new guidance that says vaccinated people should still wear masks indoors.
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Los Angeles County public health officials have also issued similar guidance, encouraging mask-wearing inside.
Now the big question -- will the Bay Area follow suit?
"I don't think so," said Solano County Health Officer Dr. Christine Wu. "I think the WHO made their recommendations because they have to provide guidance globally and many of the countries don't have the level of vaccinations that we have."
Dr. Monica Gandhi, an infectious disease specialist at UCSF, joined ABC7's program "Getting Answers" on Tuesday to answer the same question.
She said the COVID-19 vaccine covers the Delta variant very well and says the CDC has no intention of changing its guidance on mask wearing.
"There is nothing that's telling us our vaccines don't work against the Delta variant," she said.
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Data released Tuesday by Moderna shows its vaccine is likely to hold up against COVID-19 variants, including the Delta.
The Delta variant has already spread to more than 80 countries and the WHO predicts it will soon be the most dominant strain in the U.S., accounting for roughly 20 percent of the nation's cases.
Dr. Gandhi reiterated the effectiveness of the vaccines and said she does not wear a mask indoors unless a business asks her too.
Part of her decision comes from the fact that transmission in the Bay Area and California remains low.
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UCSF Epidemiologist Dr. George Rutherford says the variant is probably 70 to 75 percent more transmissible than the earliest variant strains detected.
"The Delta variant is bad news," said UCSF Epidemiologist Dr. George Rutherford. "It's much more transmissible."
He says the number of the state's COVID cases stemming from the Delta variant will mostly like double within the next month.
"The concern here is we can see small clusters of the Delta variant among unvaccinated people or those not fully vaccinated who congregate together," Rutherford said. "Particularly concerned about younger adults who've been slower to take up vaccinations."
State data shows in May the Delta variant made up 4.7 percent of California's COVID cases. That number more than tripled this month to 14.5 percent.
"The best way to prevent getting the Delta variant is to get vaccinated," added Rutherford.
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In Southern California, public health officials are now asking residents to wear a mask indoors, even if they're vaccinated.
Officials say it's a precautionary measure because of the Delta variant.
Is this something we could see in the Bay Area soon? Dr. Gandhi doesn't think so.
"I don't think San Francisco or the Bay Area will follow suit," she told ABC7.
California is close to reaching 20 million people fully vaccinated, a rate that has slowed in recent months, especially in northern counties surrounding Mendocino and Humboldt.
According to our ABC7 vaccine tracker, those northern counties are labeled in grey and white indicating only 20 to 40 percent of the county population is vaccinated.
"I think as a state it's quite possible we can back track," Rutherford said. "The whole northern tier of counties are far behind the rest of the state in terms of vaccinations."
Could the Bay Area back track too?
"Given our high vaccination rates, I don't think there's much of a chance for a surge in the Bay Area," said Rutherford.
VACCINE TRACKER: How California is doing, when you can get a coronavirus vaccine
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