California Health Officials Report Early Flu Surge and First Season Death

San Francisco health officials reported the city's first flu-related death in early October, marking an early and intense start to the 2026-27 influenza season. The California Department of Public Health states that seasonal flu activity across the state is currently moderate to high. The Bay Area records the highest flu rate in the region, while Southern California coastal and inland areas show moderate spread. Central and northern California remain at a low positivity rate for the flu virus.

Hospitalizations linked to flu complications are increasing in the Inland Empire of Southern California. Riverside University Health System and the county Department of Public Health noted that no influenza-coded deaths have been reported in that specific region as of October. However, data from the system's Epidemiology and Program Evaluation program shows current flu activity is outpacing the previous 2025-26 season. A Riverside University Health System spokesperson stated that current test positivity, hospital admissions, and emergency department visits are comparable to levels typically seen in late October or early November of the prior year.

Influenza test positivity is currently highest among children ages 5 to 17, reaching nearly twice the rate observed across all age groups. Emergency department visits are more elevated among these younger age groups, while hospital admissions are highest among older adults. The CDC advises that September and October are optimal times for vaccination because protective antibodies take about two weeks to develop. Influenza cases typically peak during the winter months, and vaccines are available at medical offices, pharmacies, and public health clinics.

This year's vaccine targets the most recently seen strain of Influenza A, according to the CDC. Wastewater SCAN reports indicate that Influenza A levels are reaching high concentrations in parts of the Bay Area. In Southern California, the Inland Empire's Regional Water Recycling Plant shows an upward trend in Influenza A over the last 21 days with high concentrations. Los Angeles County reports medium concentrations through the same monitoring network. Influenza A is included as one of the three components of the 2026-27 influenza vaccines.

Nationally, seasonal influenza activity remained relatively low in late September but was increasing. During the week ending Sept. 26, 3.4 percent of respiratory specimens tested positive for influenza, up from 2.7 percent the previous week. Of the positive flu specimens reported to the CDC in early October, 96.3 percent were Influenza A and 3.7 percent were Influenza B. The West Coast Health Alliance, a partnership between California, Hawaii, Oregon, and Washington, issued recommendations for the 2026-27 respiratory virus season. They emphasized vaccination as a primary tool for reducing serious illness and pressure on healthcare systems.

The alliance recommends that everyone age six months and older receive a yearly flu vaccine. This recommendation places particular emphasis on people at increased risk for flu complications, including pregnant people, adults 65 years and over, and infants and toddlers. Health officials continue monitoring circulating strains throughout the fall and winter to determine how closely they resemble the viruses targeted by this year's vaccine. San Francisco Health Officer Dr. Susan Philip noted that the recent death is a reminder that respiratory viruses such as influenza and COVID-19 should be taken seriously, especially for people at higher risk of getting sick.

Riverside University Health System epidemiologists cautioned that flu activity could accelerate as Californians move deeper into fall and winter. They stated that based on previous patterns, influenza activity can increase during the holiday season and winter months. Increased travel, school breaks, indoor gatherings, and family and social interactions may contribute to transmission. Dr. Philip said, "With fall festivities approaching, we want people to stay healthy and do all the fun and joyful things they want to do. Vaccines help make this happen." She added that the flu and COVID vaccines are covered by most major health plans, including Medi-Cal.

Dr. Chevinsky of Riverside University Health System stated that respiratory viruses such as influenza and RSV continue to affect the community, causing illness and placing strain on families and healthcare systems. These viruses can lead to serious complications for anyone, but especially for young children, older adults, and those with underlying conditions. Flu symptoms often come on suddenly and can include fever or chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Some people, particularly children, may also experience vomiting or diarrhea. Testing can help distinguish influenza from other respiratory illnesses, including COVID-19 and RSV.