"It is usually an illness that tells you that you are sick," said virologist Dr. John Zaia, City of Hope.
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Dr. Zaia says H1N1 hits the same way the seasonal flu does, but people know when they get it.
"People often report that they can tell you the hour that they got sick. And they will have headache, fever they can have sore throat," said Dr. Zaia.
The California Department of Health says the median age for the 69 reported cases in our state is 18.
Health officials say the flu may be spreading in children first before it strikes more older patients.
Dr Zaia says it's possible adults may have developed an immunity from previous strains.
"Flu comes in waves over generations. So even the 1957 variety may have protected from a future virus," said Dr. Zaia.
Antiviral and antibiotic drugs and better hygiene are reasons this virus may not cause widespread death as the Spanish Flu of 1918.
But Dr. Zaia says a greater number of people today are living with conditions that make them more vulnerable such as heart disease, diabetes and cancer.
"A greater proportion in our population have other things wrong with them than they did in 1918, because in 1918 if you had some of these illnesses, you died," said Dr. Zaia.
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"We will get the numbers very quickly and those numbers will tell us a lot about how to be prepared for this fall," said Dr. Zaia.
A swine flu vaccination is in the works. Experts say it'll either be included in the regular flu vaccine or it may be offered separately.