This year’s flu season started months early and in an unexpected part of the country, health officials say.
The unusually early start to the season has prompted local health officials to urge people to get their flu shots as soon as possible.
In Los Angeles County, flu activity began increasing in September, before its usual onset in early November, Dr. Dawn Terashita told The Times on Wednesday.
That’s not a major surprise, said Terashita, associate director of the Los Angeles County Department of Public Health’s Acute Communicable Disease Control Program. The flu tends to be “very unpredictable,” she said, because of the way it mutates.
But another unusual factor is that flu season has started this year in Western states.
Typically, the flu starts in the South and then spreads across the country, according to Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California.
Terashita said it was too early to know the reason for this phenomenon.
Given the first wave of the flu, Hudson said in a statement that this could have caught people off guard, as many hadn’t even had a chance to get vaccinated — or they had been so recently vaccinated that their bodies hadn’t had a chance to produce immunity to the flu.
The county’s flu season began on September 28. But the early start, Terashita noted, is not alone an indicator that the season will be more serious.
The rate of positive flu tests since the start of the season is high in the San Francisco Bay Area and moderate in Southern California and the Sacramento Valley. Flu hospitalization rates remain low across California. So far this year, there have been 34 flu-related deaths in the state, according to the state Department of Public Health’s online dashboard.
San Francisco confirmed its first flu death of the season last week. Los Angeles County has yet to record any flu deaths this season, Terashita said. During the 2025-2026 flu season, the county recorded 126 flu deaths, a relatively low total, she noted.
Kaiser has recently seen an increase in flu-related outpatient visits, although flu-related hospitalizations have not yet increased. If the current trend continues, Hudson expects hospitalizations to increase in the coming weeks.
Health officials say vaccination is the best form of protection against the flu and are urging people to get vaccinated quickly.
Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco, said people should ideally get vaccinated before mid-October. For most, he said, the standard flu vaccine is enough, although he noted there are other options, including a nasal spray version — ideal for almost anyone with a fear of needles — and higher-dose vaccines. The strongest shots contain four times more antigen and are approved for people 65 and older.
The current variant, H3N2 subclade K, appears similar to last year’s strain and is included in this year’s vaccine, reducing concerns about a major mismatch between the vaccine and the flu strain, Chin-Hong said.
“The ball is in our court because vaccination behavior determines how we fight influenza,” he said. “This year, we have fewer excuses because the flu vaccine is generally well adapted to (…) what has been circulating until now.”
Los Angeles County’s most severe flu season in recent memory was the 2009 pandemic, according to Terashita. That year, the H1N1 virus led to high numbers of hospitalizations and deaths worldwide, the Times reported at the time.
Flu cases have almost disappeared during the COVID-19 pandemic, Terashita said. As people resumed gatherings and relaxed measures such as mask wearing and social distancing, the county saw an increase in flu cases in 2024 and 2025.
“We’re watching and waiting right now” to see how serious the flu season will be, she said, “but it’s a good reminder to everyone that it’s a really good thing you can do to protect yourself, which is get vaccinated.”
Times Staff Writer Rong-Gong Lin contributed to this report.
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