CALIFORNIA STATE -California health officials are warning that influenza is picking up fast across the state, with cases and hospital admissions rising as a new strain of influenza A(H3N2) spreads. (OC Health Care Agency)
The warning comes as multiple counties have tragically confirmed flu-related deaths in recent weeks, including a child in Sacramento County and an adolescent in San Mateo County. (Sacramento County)
In total, CDPH data shows that 81 people have died from flu so far this season.
What health officials say is driving the surge
State and local health agencies are pointing to a newly emerged H3N2 strain known as “subclade K,” which has been detected in California and has been linked to waves of outbreaks in other countries. (OC Health Care Agency)
According to a health advisory shared by county public health agencies, this strain is “antigenically drifted” from the H3N2 component of the 2025-26 seasonal flu vaccine formulation, but officials stress that vaccination is still expected to help protect against severe disease.
Separately, CDPH says flu activity is increasing across all California regions, with a notable rise in test positivity among children. Hospitalizations were described as “currently low but are expected to increase.” (California Department of Public Health)
The deaths that have been publicly reported
While statewide fatality totals can lag and are typically reported through surveillance systems, several local agencies have recently confirmed deaths tied to influenza:
- Sacramento County: The county reported its first influenza-related death of the 2025-26 season on December 23, 2025, involving a child who had no underlying medical conditions; the child’s vaccination status was unknown at the time of the announcement. (Sacramento County)
- San Mateo County: The county announced on January 7, 2026 that an adolescent died in December from a flu-related illness and had not received this season’s flu shot. Officials said it was the second pediatric flu-related death in San Mateo County in 2025. (County of San Mateo, CA)
- Los Angeles County: In November, LA County officials confirmed what they described as the county’s first flu death of the season, involving an older adult with underlying health conditions who had not been vaccinated. (LAist)
What officials are urging Californians to do right now
Public health guidance is focusing on three things: vaccination, faster testing, and prompt treatment for people at higher risk.
1) Get the flu shot (even now).
CDPH and local health officials continue to recommend annual flu vaccination for everyone 6 months and older, and emphasize it is not too late to get vaccinated. (County of San Mateo, CA)
2) Test early if you get sick, especially if you are high-risk or live with someone who is.
The advisory urges clinicians to test symptomatic patients quickly and use molecular tests (including rapid molecular tests for outpatients and PCR-based options for hospitalized patients).
3) Do not wait on antivirals if flu is suspected in high-risk patients.
Health officials are urging rapid antiviral treatment (for example, oseltamivir or single-dose baloxavir, as clinically appropriate), ideally started close to symptom onset. Antivirals can shorten illness and reduce severity, but timing matters.
Symptoms to watch, and when to seek help
Flu symptoms often come on suddenly and can include fever, cough, sore throat, runny or stuffy nose, body aches, headache, and fatigue. Some people also experience vomiting or diarrhea. (Sacramento County)
Officials consistently flag higher-risk groups as including:
- adults 65+
- young children (especially under 5)
- pregnant people
- people with chronic conditions (such as asthma, diabetes, or heart disease)
If you or your child has trouble breathing, chest pain, severe dehydration, confusion, or symptoms that rapidly worsen, seek urgent medical care.
Also remember that we are journalists, not doctors. If you have any medical concerns, always contact your own doctor or healthcare provider right away.
