Dr. Soniya Gandhi, an infectious disease specialist at UCLA, said the inclusion of swine flu in this year's injection and nasal spray vaccines should help prevent the "scary" scenario from 2009.

"Swine flu had people really panicked then," she said. "I think it was because it was a newer strain — something most people hadn't been exposed to."

The U.S. Centers for Disease Control and Prevention recommends that everyone six months of age or older receive a flu vaccine each year. Getting the immunization does not guarantee that a person won't fall ill, but it does usually prevent symptoms from becoming severe in those who do, Gandhi said.

"It is by far the best protection," she said.

Dr. Oliver Brooks, associate medical director of Watts Healthcare Corp. and chairman of Immunize L.A. Families, said that many of his patients rejected flu immunizations because they considered influenza a mild illness that they didn't need to fear, or because they feared getting a flu shot would make them sick.

"The flu vaccine does not cause the flu," he said.

Typically, it takes about 10 days following immunization for the body to build up resistance to the virus, Brooks said.

The early season "is an alert for us," said Murthy, of Cedars-Sinai. "We want to heighten awareness. It's not too late to get the vaccine. There's still time, and it will still be effective."

Just because the season was beginning early, she added, did not necessarily mean it would turn out to be unusually harsh.

During 2012-2013, a "moderately severe" influenza season for Los Angeles County, 70 adults and 8 children died as a result of flu infection, according to the county public health department.


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