Santa Clara County cautions against winter illness surge
San Jose-based physician Dr. Daljeet Rai, 62, was among the first in Santa Clara County to receive the COVID-19 vaccine at O'Connor Hospital in San Jose. COVID is here to stay and staying up to date with vaccinations is recommended. File photo.

Santa Clara County is seeing a surge of COVID-like illnesses this winter, as the weather cools and people travel and gather for the holidays.

The county is experiencing a spike in respiratory illnesses, such as COVID, influenza and respiratory syncytial virus (RSV). The Santa Clara County Public Health Department tracks all three in wastewater and has seen concentrations for each illness jump in the past few months. As of December, all four sewersheds have a “high” level of COVID. San Jose, Sunnyvale and Palo Alto’s sewersheds reached concentrations comparable to levels in January 2022, when the county faced the omicron surge.  

Recent recorded COVID cases are low but the concentration of COVID in wastewater has been rising, mirroring the rise of COVID cases and waste concentration in January 2022's omicron surge.
A graph from the Santa Clara County Public Health Department shows a rising concentration of COVID in wastewater in San Jose’s sewershed, but not a corresponding rise in case number.

COVID hospitalizations began increasing in November and reached similar numbers compared to last winter, according to Dr. Monika Roy, assistant health officer and communicable disease controller with the county’s public health department.

“There’s been a steady stream of folks going to emergency rooms, seeking care for respiratory viruses,” Roy told San José Spotlight.

While county vaccination data shows more than 95% of residents have at least one COVID shot, only about 20% of the population is up to date on vaccines—with even lower vaccination rates in the Latino and African American populations at 9% and 12%, respectively.

While the county is reporting low infection numbers, there has been a uptick in hospitalizations. The state’s public health data shows about 1,905 hospitalizations from COVID and 710 from influenza as of Dec. 16, compared to 1,442 and 211 respectively as of Nov. 16.

As of December, the San Jose watershed has reached similar concentrations of COVID as it had in December 2022. The Palo Alto and Sunnyvale watersheds both are more than 90% of the way toward the concentration amounts in January 2022 and are nearing January peaks as of last year.

San Jose's watershed has "high" concentrations of COVID and is at 77% of the concentration visible in January 2022 during the omicron surge

The cold weather and people coming together over the holidays can cause surges in illnesses, Roy said. Respiratory illnesses often spike after the holidays because the peak season isn’t over, but how the virus will react is hard to predict, she said. Roy added that COVID is especially difficult to predict because it’s still a newer virus.

Roy also said it’s possible for various respiratory illnesses to spike one after another. Last year, there was a spike in RSV, followed by jumps in influenza and COVID, but the cycle could play out differently this year, she said.

“One virus may predominate at one time, but then you might see another wave of another virus,” Roy told San José Spotlight. “That’s why we rely so much on our wastewater data and our emergency room visits to help us understand what we’re seeing in real time.”

Getting vaccinated is still one of the best ways to protect against illnesses, along with covering one’s mouth when coughing and masking when in a group, Roy said.

Dr. Yvonne Maldonado, a professor of global health, infectious diseases and epidemiology at the Stanford University School of Medicine, said the past few years of dealing with COVID have increased people’s awareness of respiratory illnesses, and people might not be as worried as before. Maldonado said that while vaccines are contributing to increased immunity throughout the community, it’s also led to a decrease in COVID’s perceived risk.

“Every decision we’ve made about this pandemic and about flu and RSV, all of this, is about the perception of risk, because there’s no 100% guarantee that you are going to get infected or not infected. And if you do get infected, there’s no guarantee that you’re going to be in the hospital,” Maldonado told San José Spotlight. “But the risks are never zero, so it’s about how people gauge their own risks.”

Contact B. Sakura Cannestra at [email protected] or @SakuCannestra on X, formerly known as Twitter.

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