During a press briefing Wednesday with city officials, Dr. Grant Colfax said a crisis like what was seen in New York earlier this year could be just a few months away.
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"I'm very concerned as cases increase, it's plausible we could get to a New York-like situation in the late summer, early fall," Dr. Colfax said.
The new testing sites Breed announced Wednesday will allow for an additional 1,400 San Franciscans to be tested for the virus each day.
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San Francisco has a total of 5,469 cases of COVID-19 as of Wednesday.
"We have flattened the curve before and we must do it again," Colfax said.
Dr. Colfax said on average San Francisco has 79 new diagnosed COVID-19 cases each day.
"These numbers put us in the red zone," Colfax said. "As of tomorrow, we will have been in the red zone for a month."
San Francisco was added to the state's virus watch list on Friday, which forced indoor malls and non-essential offices to close Monday.
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San Mateo County remains the only Bay Area county not on the state's watch list for COVID-19.
The new mobile testing sites the mayor announced will be able to conduct 250 tests each per day and will rotate to different parts of San Francisco where testing is most needed. One of the sites launches this week and another next week, Breed said.
This update from San Francisco's mayor and other city officials comes as cases continue to steadily rise in California, which surpassed New York Wednesday as the state with the highest number of positive cases.
Dr. Colfax did point out one promising trend.
RELATED: California sees record-breaking number of new COVID-19 cases, Gov. Newsom announces
"San Francisco has the lowest rate of COVID-19 cases and deaths, and the highest rate of testing when compared to other jurisdictions like Los Angeles, Denver, Boston, and New York," he said.
Last week, the city announced it took 38 days for cases in San Francisco to increase by 1,000. Now, Dr. Colfax said the city is now seeing spikes like that in 13 days.
"I'm tired of living with COVID-19 just like you are," Breed said. "But, the sooner we act responsibly, the sooner we can get back to reopening our city."
California reported more than 12,800 COVID-19 cases in just a 24-hour period, Gov. Gavin Newsom announced Wednesday during his update on the pandemic.
This is the highest number of cases reported in one day in California since the start of the pandemic.
As of Wednesday, California has more than 413,000 cases of the virus.
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