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California’s New Coronavirus Dip Does not Match Wastewater Surveillance Data

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By Zhihui Zou

June 12, 2022
5:54 am
Los Angeles, CA

There is no doubt that coronavirus mutates and creates new variants quickly. Subvariants of the now-dominant omicron have reached stage BA.5 in the state of California. Subvariant BA.1 was seen in March. April saw BA.2. Covid cases dropped slightly in California, by around 6%, in the second week of June, according to Los Angeles Times. Despite all California counties still having high virus transmission rate (defined as 100 cases per 100,000 people), many counties, such as Orange, Riverside, San Diego, and Ventura Counties, have seen decrease in average Covid cases compared to previous week. Meanwhile, Los Angeles County saw a 10% increase, and San Bernardino and Santa Barbara Counties both saw some degree of increase in case rates. Many sources report that the case data for the second week

Covid cases dropped slightly in California, by around 6%, in the second week of June, according to Los Angeles Times. Despite all California counties still having high virus transmission rate (defined as 100 cases per 100,000 people), many counties, such as Orange, Riverside, San Diego, and Ventura Counties, have seen decrease in average Covid cases compared to previous week. Meanwhile, Los Angeles County saw a 10% increase, and San Bernardino and Santa Barbara Counties both saw some degree of increase in case rates.

Ventura, California © Tamara Lee Harding | Dreamstime.com

Many sources report that the case data for the second week of June might not be accurate due to the Memorial Day weekend. As summer holiday approaches, sources also believe that cases will rise again due to travels and gatherings.

California’s wastewater surveillance data, the surveillance of coronavirus in the sewer system, does not seem to match with the overall decreasing trend. Center for Infectious Diseases’s deputy director Dr. Erica Pan said “we have many more cases than we are reporting, absolutely. I think our wastewater surveillance shows that as well, that the trends in certain areas are as high as in the middle of the omicron surge.”

Wastewater data is often used to predict coronavirus spread without having to test person to person. “It doesn’t depend on you having access to health care or health insurance,” Newsha Ghaeli, the president of the wastewater epidemiology company Biobot Analytics, said.

Omicron subvariants BA.4 and BA.5 might be wastewater data’s proof. BA.4 has been detected in Santa Clara County, the county with the highest case average right now, and is slowly growing in Los Angeles County as well.

“The increases in BA.4 and BA.5 have also been seen across the state,” Barbara Ferrer, Los Angeles County Public Health Director, reported. Ferrer has also reminded people to get vaccine boosters and wear masks when indoor.

Alameda County, San Francisco Bay Area’s second most-populated county, reinstated the indoor mask mandate on June 3rd. When the mandate was reinstated, Alameda County saw 354 cases per 100,000 people in a week, one of the highest transmission rates by county.

Los Angeles County is also not looking great. Currently, LA County sees a covid-positive hospitalization rate of 6.4 per 100,000 people by Friday, June 10. This is a 21% increase compared to the week prior. The threshold for “high Covid community level” is 10 per 100,000 people, and Santa Clara County has reached it with a rate of 10.1 per 100,000 people.

People waiting in line to enter a recently reopened DMV office; they are wearing masks and are social distancing. © Andreistanescu | Dreamstime.com

Dr. Sara Cody, Santa Clara County’s public health director, said that what is not happening with this new wave of coronavirus is “a lot of people who are getting seriously ill and requiring hospitalization for their Covid infection.” Meanwhile, the new subvariants are being reported as more contagious than previous variants.

As for now, Santa Clara County does not have an indoor mask mandate.

“The subvariants that are circulating keep changing and evolving. It’s not just one, it’s multiple. And I don’t really know what that’s going to look like over time,” Dr. Cody said.

Like Dr. Cody, many health officials have shared the unstable changes of Covid variants. “We have the possibility now of starting to see more BA.4 and BA.5. Will they crowd out BA.2.12.1? We have no way of knowing…” Ferrer said.