Here's why San Francisco has the highest COVID positivity rate in California

SAN FRANCISCO -- As COVID cases rise across the state and the country, the San Francisco Bay Area has the highest positivity rates in the state.

According to state data, San Francisco's positivity rate was 7.7% on Thursday.

When asked why San Francisco is seeing such a high positivity rate, University of California, San Francisco's Dr. George Rutherford said there are a lot of factors to consider.

"There's lots of different possibilities, but I think it probably will come down to other parts of the state had higher levels of infection recently in December, January, February, and that's more protective than the vaccine in the very short run," said Dr. Rutherford.

Natural acquired immunity from COVID is what Rutherford is referring to. Basically, the idea that people in other areas of California already had the new variants of COVID in recent months.

"The people who weren't exposed are going to get exposed. That's why even in San Francisco the wealthiest communities are being affected disproportionately now," said UCSF's Dr. Peter Chin-Hong.

Communities that hadn't previously been hit as hard.

Another possible reason for our 7.7% COVID positivity rate in San Francisco.

"We test more than other places. We still have testing sites, people are really aware, we are told to test. There is a lot more testing probably happening here," said UCSF's Dr. Monica Gandhi.

The four doctors we spoke with Thursday agree. Vaccines and boosters are keys going forward, even for younger age groups that are now seeing higher transmission rates.

"You have a lot of people who are less vaccinated, haven't been boosted, who are in their 20's and 30's here than we used to have and that's where the transmission is going on," said Dr. Rutherford.

The good news, despite the higher positivity rate in San Francisco, according to state data, hospitalizations remain low and we haven't seen COVID-related deaths since mid-April. Doctors say that's a credit to the vaccines and boosters.

"We're going to have to learn to live with this virus and the bottom line is low hospitalization rates and zero mortality," says Dr. Rutherford.

"Hopefully cases will peak in two weeks and then come down by the end of May, so hopefully we're looking at a better summer," says Dr. Gandhi.

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