North Bay has seen a surge in COVID-19 cases over the summer, partly due to the more contagious FLiRT variants and low vaccination rates, a local health expert said Wednesday.
Sonoma County Health Officer Dr. Tanya Phares said the current “summer wave” of COVID-19 infections is a familiar trend during the pandemic, but it is exceeding that of last year.
“The current summer wave is outpacing 2023, but not 2022,” Phares said. “This is a national trend, but we appear to be seeing a similar trend in Sonoma County.”
The latest local wastewater surveillance data for SARS-CoV-2, which causes COVID-19 disease, shows that this summer’s outbreak appears to have occurred earlier than last year.
On June 27, the “composite” levels of COVID-19 detected at wastewater treatment plants in Santa Rosa, Petaluma and Windsor were 56% of their highest levels ever recorded during the pandemic.
On the same day last summer, it was 8 percent. Looking just at Santa Rosa, the level on June 27 this summer was 61 percent, compared to 8 percent on the same day last summer.
Detection of COVID-19 in local wastewater has been increasing since late April, and Phares said it’s unclear whether COVID-19 infections simply peaked earlier this summer or if infection rates will continue to rise.
“It’s possible that the peak has passed early or that it could continue to rise, but it’s very hard to predict what will happen,” Fares said. “We’ve seen different mutations with each peak over time, so we’re dealing with a different problem each time.”
Fares said national and European trends suggest that so-called FLiRT variants, descendants of the Omicron variant, continue to circulate. The dominant FLiRT variant domestically is KP.3, while KP.3.1.1 is expected to increase fairly rapidly in the U.S. and Europe, he said.
Fales said the current surge in cases is concerning given the county’s low vaccination rates.
Overall vaccination coverage (the percentage of the population that is up to date on COVID-19 vaccinations) is 23%. Even in the most at-risk age group, those 65 and older, the vaccination coverage is just under 56%.
The latest vaccination rate across Napa County is about 21%, and for those 65 and older it’s 51%.
Dr. Gary Green, an infectious disease specialist at Sutter Santa Rosa Regional Hospital, said vaccine fatigue and pandemic fatigue likely contributed to the current low vaccination rates this summer.
Green said Sutter Hospital is seeing a “summer outpatient surge” with the majority of COVID-19 patients being seen as outpatients.
He noted that there has also been a “slight increase” in COVID-19 hospitalizations and emergency room visits, but “it’s not a surge.”
Green said he believes the rise in cases could be due in part to weakened immune systems and people not taking proper precautions, as well as increased summer travel.
He said extreme summer heat across the country may also be contributing to the increase in people staying indoors and coming into close contact with each other.
“I think the heat wave is driving people indoors and to malls and indoor shopping because it’s just too hot,” he said. “I think crowds spread the virus.”
Green said 30% of nasal swab tests administered in outpatient clinics are currently testing positive. For comparison, the start of flu season is typically declared when swab test positivity reaches 10%, he said.
Green said 16% of COVID-19 test results are coming back positive in emergency departments.
Fares said COVID-19 deaths remain low but steady, posing a particular threat to the most vulnerable groups, including frail elderly people and those with chronic illnesses or weakened immune systems.
She said there have been 39 deaths from COVID-19 so far this year, less than 10 per month.
“The message really is that we have to remain vigilant and we have to work to increase vaccination rates to protect ourselves and reduce the spread of the disease and prevent mutations,” she said.
Staff writer Martin Espinoza can be reached at 707-521-5213 or martin.espinoza@pressdemocrat.com. On Twitter: @pressreno.
