La Oferta

February 29, 2024

Flu and other respiratory viruses increasing in Santa Clara County

Wastewater data offers new insight into flu spreading locally

Santa Clara County, CA. Nov. 16,2022– New data show that flu activity is higher in Santa Clara County than usually seen at this time of year, with levels increasing since the start of November. County of Santa Clara Public Health Department data show the weekly percentage of emergency department visits for influenza-like illness is about triple what it was for the same time period during the 2019-2020 flu season, right before the COVID pandemic.

Today, Public Health is adding a new tool for the public to track flu transmission and risk in communities. Building on techniques developed during the COVID pandemic to track community virus spread through wastewater analysis, Public Health today published wastewater data for flu concentration, one of the first dashboards of its kind from a local public health department in the country.

“Flu is here and on the rise. These new data are a good reminder that it is not too late to get a flu shot,” said Dr. Sara Cody, Health Officer for the County of Santa Clara and Director of the Public Health Department.  “Seeing rising levels of flu in wastewater provides us with an early indication of community risk, and alerts health systems to a potential surge in patients.”

This is the first winter in which Santa Clara County faces not only increased flu and COVID activity, but also unusually high levels of RSV, which is most affecting young children and the hospitals and doctor’s offices caring for these families. There are safe and effective vaccines for flu and COVID; they offer the best protection against severe illness. Since there is no vaccine for RSV, it is especially important that people wash their hands, cover coughs and sneezes, and stay home when sick.

“Our early indications, from the number of patients seeking treatment and hospitalizations for flu and RSV, have our medical staff preparing for an influx of people seeking treatment in our hospitals and clinics,” said Dr. Vidya Mony, Pediatric Infectious Diseases Specialist, Associate Hospital Epidemiologist at Santa Clara Valley Medical Center. “Our care teams are already working to safely meet the needs of our patients.”

What you can see with wastewater data

Unlike test results from doctors’ offices or hospitals, wastewater gives data on everyone living in all residences connected to the sewer, including the many people who never get tested because they can’t afford the time off or cost to see a doctor.

The new web page at is updated weekly and shows flu concentration in each of the four Santa Clara County sewersheds: Gilroy, Palo Alto, San Jose, and Sunnyvale. People can view if flu transmission is increasing or decreasing in their communities and how the current level compares to previous weeks and months. The dashboard tracks influenza A, the type of flu most likely to land someone in the hospital or worse. Data shows more flu than was the case during the first two years of the COVID pandemic, when there was less flu likely due to COVID prevention activities like masking and distancing that also prevent flu.

Levels of virus and transmission can vary greatly in different parts of the County and fluctuate. Data show levels of influenza A are above where they were in late October across all four sewersheds.