'Over 50% of the strains': UCSF doctors detect shocking increase of CA variant cases in Mission District study

SAN FRANCISCO (KGO) -- Doctors report an increase of California variant cases in San Francisco's Mission District and point to an elevated transmission within households.

On Dec. 31, UCSF infectious disease specialist Dr. Charles Chiu detected the first California variant cases in the Bay Area. Now, it's been close to two months and the health care community is concerned as cases increase.

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"This is a race against the virus," said Dr. Diane Havlir, UCSF Professor of Medicine, HIV, Infectious Disease, and Global Medicine, Infectious Diseases.

"This is a race against time," said Jon Jacobo, health committee chair with the Latino Task Force.

"It's a race between us and the variant and we don't want to lose," said Dr. Joe DeRisi, professor of biochemistry and biophysics at UCSF and co-president of Chan Zuckerberg Biohub.

Community group Unidos en salud, the Latino Task Force, along with Chan Zuckerberg Biohub and UCSF found that, over the holidays, the California variant was spreading not only in the state but locally in the Mission District.

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"Comprised approximately about 16% of all the virus we were seeing people infected," said Dr. Havlir.

A month later, in January, they were shocked. "It now is comprising over 50% of the strains we are seeing," said Dr. Havlir.

Over 8,000 people in the Mission District were part of the month-long study.

"What is concerning to me is knowing that we are, at any point in time, waiting for a new variant that could be more infectious and more deadly," said Jacobo.

Half of the 883 people from the study who tested positive for COVID-19 did not have symptoms, according to Dr. DeRisi.

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Luz Pena: "Based on the data that you are gathering, why is it that the California variant is spreading so quickly in this community?"

Dr. Joe DeRisi: "It has a modest but consistent increase in that so-called attack rate. That is the proportion of people who get sick when a sick person comes to the house."

Dr. DeRisi says the California variant is not as aggressive as the UK and South African variants.

One of the many concerning traits of the California variant is that it's spreading fast among households.

As Dr. Havlir sees the increase first hand, she says the main key to stop the California variant and others from mutating is to vaccinate as many people as possible and added, "The virus does not care about boundaries. It's going to spread widely quickly so it's much higher for these variants to pop out when there is so much virus replicated."

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