Flu activity in Riverside County surged to "very high" levels during the week of Oct. 18-24, driven by a rapid rise in positive tests, according to the county's weekly influenza surveillance report.
The formal flu season does not begin until Nov. 1. Statewide, the virus has already claimed 87 lives, including at least three children, as of mid-October, Patch reported.
No flu deaths have been reported in Riverside County this season, according to the surveillance report. But in neighboring San Bernardino County, an infant with underlying medical conditions became the first pediatric flu death of the 2026-27 season, the Press-Enterprise reported Oct. 30. The child was too young to receive a flu shot.
San Bernardino County Health Officer Dr. Sharon Wang urged residents who qualify to get vaccinated and work to limit the spread of illness, according to the Press-Enterprise.
Kids hit hardest in testing
Influenza A(H1N1) is the predominant circulating strain in Riverside County, the surveillance report said. Influenza-associated emergency department visits and hospital admissions are both increasing, though both remain at low activity levels.
Children are bearing a disproportionate share. A Riverside University Health System spokesperson told Patch in early October that flu test positivity among children ages 5 to 17 was running at nearly twice the rate seen across all age groups. Emergency department visits were more elevated among younger age groups, while hospital admissions were highest among older adults, the spokesperson said.
"This season appears to have started earlier than in recent years," the RUHS spokesperson told Patch. "Current influenza test positivity, hospital admissions, and Emergency Department visits are already comparable to the levels we typically saw in late October or early November last season."
That early start matters. During the 2025-26 season in San Bernardino County, the first pediatric flu death did not come until February, the county's public health department said.
Wastewater signals climbing
Wastewater monitoring adds another warning sign. The Inland Empire's Regional Water Recycling Plant showed an upward trend in Influenza A concentrations over 21 days, with high levels, Patch reported. Two wastewater facilities in Riverside County participate in the WastewaterSCAN monitoring network, according to the county surveillance report.
The California Department of Public Health rated Southern California's coastal and inland flu activity as moderate, Patch reported. The Bay Area had the state's highest rate.
Where Temecula residents can get vaccinated
The CDC advises that protective antibodies take about two weeks to develop after a flu shot, Patch reported. Annual flu vaccination is recommended for everyone 6 months and older, with particular emphasis on young children, adults 65 and older, pregnant people and those with certain chronic health conditions.
Riverside University Health System Community Health Centers offer free flu shots Monday through Friday, 8 a.m. to 11 a.m. and 1 p.m. to 4 p.m., according to the RUHS respiratory viruses page. No appointment is needed. Residents can call 800-720-9553 for locations and updates.
RUHS also lists upcoming vaccination clinics across the county, including sites in the Temecula area. Walk-ins are accepted. For questions about eligibility, call (951) 358-7125, Monday through Friday, 8 a.m. to 5 p.m.
RUHS epidemiologists cautioned that flu activity could accelerate during the holiday season and winter months, when travel, school breaks and indoor gatherings increase transmission, Patch reported.
