SAN FRANCISCO (CBS SF) — UC-San Francisco researchers have detected a dramatic rise since mid-January of COVID-19 variants, particularly L452R, among those found to be infected with the virus living in the city’s predominantly Hispanic Mission District.

The study also identified one case of P.2 – a variant first identified in Brazil – though contact tracing suggests there was no forward transmission of that variant of the virus.

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Researchers said the other new variants — L452R substitution and two other mutations — initially appear to be more contagious, although further research is needed.

The finding came in a joint testing project between UCSF, the nonprofit Chan Zuckerberg Biohub and Unidos en Salud to slow the spread of COVID-19 in the Mission District.

“The research findings indicate that the L452R variant represents 53% of the positive test samples collected between January 10th and the 27th,” said UCSF infectious disease expert Dr. Diane Havlir. “That is a significant increase from November when our sequencing indicated that this variant comprised only 16% of the positive tests.”

This virus lineage, sometimes referred to as CAL.20C, has previously been detected in other U.S. locations including California and is now increasingly being found in multiple counties throughout the state.

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In January, Unidos en Salud conducted a COVID-19 study using the BinaxNOW rapid antigen test to collect and analyze positive results. A total of 8,846 people were tested as part of the month-long study.

Genomic sequencing of the virus from over 630 positive samples was used to monitor for the emergence of new variants or introduction of new viral strains, providing an accurate view of which viruses are circulating in the community.

With the assistance of the Mission District community, the collaborators were also able to investigate key questions about household transmission, symptoms and infections in children.

According to the research findings, the L452R variant appears to be more transmissible than other strains.

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“The research indicates that the household secondary attack rate of the L452R variant identified in the Mission District appears to be higher than other rates that have been measured within the United States and globally, but more work needs to be done to confirm these findings,” said CZ Biohub co-president Joe DeRisi.