The Central Valley has the highest level of flu activity in California. 

As the U.S. reaches peak flu season, the Bay Area is dealing with the second highest level of flu cases in the state. 

Currently, 18% percent of respiratory tests in the Bay Area are coming back positive for the seasonal influenza virus, according to the California Department of Public Health. Only Central California, including Fresno, has higher levels in the state, with 21% of tests coming back positive for the flu. 

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Nationwide, the Centers for Disease Control and Prevention reports seasonal flu activity has ramped up sharply after the holidays. Currently, 45 states are reporting high or very high flu activity, according to the CDC. And the percent of people showing up with flu-like symptoms for outpatient medical care is the highest it’s been in the past five years.

Dr. Eric Ball, a pediatrician based in Orange County, said flu patients tend to have fever, cough, body aches and........

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