While COVID-19 cases in Santa Clara County have trended down over the summer, the county's top health official said this week that the level of virus circulating locally is likely higher than the county's case count.

Health Officer and Public Health Director Dr. Sara Cody said Tuesday that the number of cases locally has decoupled since May from the amount of virus detected in the county's main sewershed in San Jose, which captures sewer water — and by extension, COVID virus particles — from more than 75% of the county's population.

As a result, the amount of virus present across the county is likely two to three times higher than it appears by just looking at the county's seven-day average case count.

"If you look just at the reported case counts, you would conclude 'a ha, we're in the clear, we're almost safe again,'" Cody told the county's Board of Supervisors. "But if you look at the wastewater, you can see, unfortunately that's not really the case.

"There's still a significant amount of virus circulating and therefore our risk of exposure still remains elevated," she said.

COVID-19-related hospitalizations have also declined along with COVID-19 cases and virus levels in local sewersheds, but Cody noted they are not down to the nadirs they reached between previous waves.

As of Friday, 123 patients were hospitalized with COVID-19 across the county.

"Hospitals are managing and in pretty good shape, but I wouldn't say that they're totally out of the woods as far as needing to provide care for COVID patients," Cody said.

COVID-19-related deaths during the most recent wave of cases tied to subvariant strains of the omicron variant remained far below the peaks of previous surges, which reached levels of 50 deaths per day or more.

That said, the county has still confirmed roughly 500 COVID-19-related deaths since the start of 2022.

The relatively flat death rate, Cody suggested, is due to the county's high vaccination rate and, among unvaccinated residents, immunity from previous infection.

As of Monday, 87.3% of county residents had completed their initial vaccination series and 69% of booster-eligible residents ages 5 and up have received at least one booster vaccine dose.

"The good news ... is that we're not seeing these big surges in people dying of COVID, and in large part I think that's due to widespread vaccination and boosters," she said. "Pretty much the whole population has some immunity of one kind or another."

Cody declined to speculate on how the virus could behave in the winter, citing the unknown of how future variants will coexist with the protection from serious illness that is provided by the available COVID-19 vaccines.

"I can't tell you exactly what's around the corner," she said. "But I can tell you about what we know now and what we can continue to do to keep each other safe, even as we return to something that feels, at this point, pretty normal, which is nice."