Mutated COVID-19 variant could be behind surge in SF virus levels

New data shows COVID-19 is circulating at the highest level of the year for much of the Bay Area, and experts warn a surge could be coming with the start of the school year.

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Many parts of the Bay Area, including Marin, Palo Alto, Sunnyvale and San Jose, show high and, in some cases, rising levels of the virus, according to data from WastewaterSCAN, which detects the virus via wastewater treatment plants. Other areas show medium levels of the virus, while Gilroy, the sole outlier in the Bay Area, shows low levels.

In San Francisco, data from recent weeks shows the city has had the highest levels of COVID-19 since September of last year. The city is also seeing an increase in hospitalizations and positive COVID tests. 

Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco, said the start of a new school year, which begins on Monday in San Francisco and has already started in Oakland and San Jose, could push disease levels higher.

“Whenever people get together, large groups, that’s often a time you worry about things just spreading more efficiently,” he told SFGATE. “What might look like a cold in say an adolescent or somebody in middle school could translate into something more serious in an older grandparent if they brought it home.”

Since the pandemic, the COVID-19 virus has settled into a pattern where it surges in both summer and winter months. However, the recent increase shows levels of the virus were much higher than last winter. Chin-Hong noted the recent increase could be due to a heavily mutated variant dubbed the cicada variant. 

In early July, a growing percentage of COVID-19 cases were linked to the BA.3.2 or cicada variant, according to data released from the U.S. Centers for Disease Control and Prevention. 

“Whether or not it settles into summer disease would be interesting mainly, but I still don’t see a pattern per se yet, and it may be driven by new variants,” he said. 

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Chin-Hong said a newly formulated COVID-19 shot will be released this fall, but older adults or those who are at high risk of severe disease can get a booster shot earlier if they are concerned about rising cases.

Chin-Hong noted experts are still watching to see how COVID-19 will change in its spread and impact year on year. He pointed out that this year, the number of hospitalizations, while increasing, hasn’t risen sharply despite the high levels of viral activity, which may be due to a changing virus or better herd immunity.

“What I’m hoping is that we will have fewer people actually get more seriously ill this year compared to last year, even though the COVID is circulating,” he said.

However, he said, it’s still possible the Bay Area will see a major surge in hospitalizations in the coming weeks. 

“Time will tell,” he said. “We’re due to get more cases now, based on the time when people’s immunity kind of drops.”