The flu season has arrived early in LA County, prompting public health officials to strongly urge residents to get vaccinated as soon as possible. While influenza typically originates in the southern and southeastern regions before spreading westward, this year has seen an unusual pattern with the virus spreading first in the western region.
Don Terasita, deputy director of the Acute Communicable Disease Control Program at the LA County Department of Public Health, stated on the 7th that flu activity, which usually increases from early November, began rising as early as September. The official start date for the county’s flu season was recorded as September 28.
Terasita explained that because influenza viruses continuously mutate, it is difficult to predict the exact trajectory of the outbreak, and the early start does not necessarily mean the impact of this season will be more severe.
The region where the outbreak began also differed from previous years. Dr. Helen Chu of the University of Washington noted that because influenza generally starts in the South and Southeast and moves north and west, the West Coast typically experiences the latest outbreaks. The reason for the early spread in the West this year has not yet been confirmed.
In California, test positivity rates since the start of the season have been high in the San Francisco Bay Area and moderate in Southern California and the Sacramento Valley. However, flu-related hospitalization rates remain low across the state.
According to California Department of Public Health data, there have been 34 flu-related deaths statewide this year. San Francisco confirmed its first flu death of the season last week, while LA County has not yet reported any flu fatalities. Terasita noted that during the 2025–2026 season, the county recorded 126 flu deaths, which was a relatively low figure.
Health experts emphasize that vaccination remains the most effective tool for preventing the flu and recommend early immunization. Dr. Peter Chin-Hong, an infectious disease expert at UCSF, advised getting vaccinated preferably by mid-October.
Chin-Hong explained that while standard flu vaccines are sufficient for most people, other options include nasal spray vaccines and high-dose vaccines approved for adults aged 65 and older. High-dose vaccines contain four times the antigen content of standard shots.
He added that the currently circulating H3N2 lineage ‘subclade K’ is similar to last year’s virus and is included in this year’s vaccine, reducing concerns over a mismatch between the vaccine and circulating strains.
‘How we respond to the flu depends on vaccination,’ Chin-Hong emphasized. ‘Given that previously circulating viruses and this year’s vaccine match up well overall, getting vaccinated is even more important.’
Terasita noted that the flu, which nearly vanished during the COVID-19 pandemic, resurged following the resumption of gatherings and the relaxation of mask mandates and social distancing, with cases increasing in LA County through 2024 and 2025.
‘We are monitoring how severe this season will be,’ he said. ‘Getting vaccinated is a very good way to protect yourself.’
