Wastewater Testing Still Shows High COVID Transmission, California's Epidemiologist Says

Wastewater monitoring may show a clearer picture of virus spread compared to new county data that relies on testing, which shows COVID cases may be easing

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San Diego County reported Thursday COVID-19 infections are down nearly 300 cases from about a week ago, but that does not mean less people are getting infected, California's epidemiologist says.

Part of why the county may not have the most accurate case numbers is because more people are using at-home covid tests, that aren’t always reported it to health officials.

“We have many more cases than we are reporting, absolutely,” California Department of Public Health epidemiologist Dr. Erica Pan said. “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.”

Dr. Pan is also deputy director of the Center for Infectious Diseases. The department is monitoring trends through wastewater surveillance which captures the presence of covid in our sewer system.

There are different factors leading to the increase in cases over the last several weeks, including holiday gatherings, people letting their guard down and new COVD subvariants, Dr. Pan said.

“The BA.2.12.1 is about 50% of what we're seeing right now, Pan said. “The newest one, BA.4 and BA.5 is probably around 4% in some of our recent sequencing, and we'll continue to monitor that trend.”

The state is also monitoring hospitalizations and positivity rates.

In the last two months, the number of positive cases has fluctuated, but the positivity rate, has steadily increased from about 3% on April 9 to close to 12 percent on June 4.

Meanwhile, hospitalizations remain low compared to earlier surges.

Dr. Pan said there are no indications that any of these subvariants cause more severe illness or hospitalizations, but it is more infectious.

Experts predict there could also be a lag in reporting from Memorial Day weekend and transmission could worsen as vacation and summer gatherings increase. Experts are still recommending getting boosted because immunity wanes over time.

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