When should I get my flu shot in California? How to protect yourself this fall

The start of fall is underway in California.

With it comes the beginning of another respiratory virus season.

Two types of influenza — A and B — are responsible for the seasonal flu epidemics that sicken people, according to the California Department of Public Health.

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Influenza viruses can circulate year-round, but activity typically increases during the fall and winter months.

“Many respiratory viruses, including flu, (respiratory syncytial virus) and COVID-19 circulate year-round in the United States,” the state Public Health Department said. “Some viruses are more active from October through March, such as the flu and RSV among many others.”

The federal Centers for Disease Control and Prevention estimated that the 2024-25 season resulted in about 51 million illnesses, 23 million medical visits, 710,000 hospitalizations and 45,000 deaths in the United States.

While final numbers for the 2025-26 flu season have not yet been released.

Here’s what to know about flu symptoms, how the virus spreads, when to get vaccinated and how to “protect yourself from flu” this fall:

When is flu season in California?

According to the California Department of Public Health, the 2026-27 respiratory virus season is from July 5 through July 3, 2027.

Influenza activity typically begins increasing in the fall and peaks during the winter months.

As of Monday, Sept. 21, overall flu activity in California was “low,” according to data from the California Department of Public Health.

Test positivity was also “low” statewide, although activity varied by region. Northern California was classified as “very low,” while the Bay Area was at a “moderate” level.

Hospital admissions for flu remained “very low statewide,” as of Monday. While wastewater concentrations were “low” overall, there were higher levels detected in Northern California.

How does the flu spread?

According to the CDC, the flu spreads mainly through respiratory droplets released when an infected person coughs, sneezes or talks near other people.

“These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs,” the CDC said.

Flu can also spread when someone touches a surface contaminated with the virus and then touches their mouth, nose or eyes.

People with flu can spread the virus before they realize they’re sick, according to the CDC.

“Putting physical distance between yourself and others can help lower the risk of spreading a respiratory virus,” the CDC said.

What are flu symptoms?

The flu can be detected in infected people beginning about one day before symptoms appear and for roughly five to seven days after patients become sick, according to the CDC.

People are generally most contagious during the first three days of illness.

According to the CDC, common flu symptoms include:

• Fever or feeling feverish, with chills
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headache
• Fatigue or tiredness

“Some people may have vomiting and diarrhea, though this is more common in children than adults,” the CDC said.

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Who is most at risk for flu?

Some people are more likely to develop serious complications from the flu, including adults 65 and older, young children, pregnant people and people with certain health conditions, such as asthma and kidney disorders.

Complications can include pneumonia, hospitalization and, in severe cases, death, according to the CDC.

How can I prevent getting the flu?

The CDC recommends taking “everyday preventive actions” to reduce the spread of flu and other respiratory viruses.

This includes avoiding close contact with people who are sick; covering your coughs and sneezes; washing your hands frequently with soap and water; and avoiding touching your eyes, nose and mouth.

“The best way to reduce your risk from seasonal flu and its potentially serious complications is to get a flu vaccine every year,” the CDC said.

When should I get my flu shot in California?

Updated flu vaccines are available now, the California Department of Public Health told The Sacramento Bee.

Californians can get a flu vaccine through their health plan, health care provider, local public health clinic or federally qualified health center.

Residents can also search for a vaccination clinic through My Turn, the state’s vaccine scheduling and information site.

The California Department of Public Health recommends that Californians get their flu vaccine in September or October to “optimize protection before influenza viruses start to spread in the community.”

“Ideally, everyone should receive flu vaccination by the end of October for optimal protection before the influenza season,” the department said.

How long does a flu vaccine protect you?

The California Department of Public Health said protection from the flu vaccine is “expected to last the duration of the influenza season.”

“It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection,” the department said.

That means people who get vaccinated in September or October should generally have protection in place as flu activity increases later in the fall and winter.

How often should I get a flu vaccine?

For most people, one flu vaccine dose is recommended each flu season.

However, some children ages 6 months through 8 years might need two doses if they have not previously received two doses of flu vaccine, according to the California Department of Public Health.

According to the CDC, flu vaccination is recommended annually because influenza viruses change over time and the vaccine is updated for new flu seasons.