SACRAMENTO (CBS SF) -- Two more influenza-related deaths were reported in Alameda County on Friday after the state Department of Public health announced fatal infections of the virus from throughout the state.
There have been three cases of H1N1 strains of the flu leading to deaths in Alameda County since the beginning of the winter season, county public health department spokeswoman Sherri Willis said.
One was reported earlier this week and two more confirmed cases came in Friday, she said.
The three make for a total of 11 flu deaths that have been reported in Bay Area counties, including two in Marin County, two in Santa Clara County, and one each in San Mateo, Sonoma, Contra Costa and San Francisco counties.
California Department of Public Health doctors said seven confirmed influenza deaths of people under age 65 have been reported this season up until Jan. 4. There are 28 more influenza-related deaths are under investigation.
Six of the seven deaths reported by the state were from the H1N1 strain.
The seven deaths as of Jan. 4 were in Alameda, Contra Costa, San Francisco, Lassen, Los Angeles, Sacramento and Stanislaus counties.
None of the seven deaths were children, said Dr. James Watt, chief of the Division of Communicable Disease Control in the state's Department of Public Health.
The 28 deaths under investigation were reported after Jan. 4.
This season's H1N1 influenza strain is challenging and is affecting young adults and children, said Dr. Gil Chavez, the state's epidemiologist and deputy director of its Center for Infectious Diseases.
At least two of the seven who died had not been vaccinated and the vaccination status of the other five is unknown, Chavez said.
Chavez said the number of confirmed influenza deaths is expected to rise by next Friday when the state releases the latest figures provided to the Department of Public Health from county public health departments.
Like the H1N1 influenza epidemic in 2009, the H1N1 virus this season does not discriminate by age, health officials said. The H1N1 virus in 2009 killed 607 people in California, Department of Public Health officials said.
The flu season typically peaks in February or March.
Those most at risk of contracting the H1N1 virus are the elderly, pregnant women, infants and people with other health conditions.
In a news release Friday, Dr. Ron Chapman, director of the California Department of Public Health, said the increase in flu activity is not unexpected and said it is not too late to get a flu shot.
"California is seeing an accelerated increase in flu activity over the past few weeks. You can help prevent further spread of the flu by getting a flu shot," Chapman said.
H1N1 is the predominant strain contained in this season's flu vaccine. The vaccine also contains the H3N2 and influenza B strains. It takes two weeks after an inoculation to be fully protected but the vaccine provides some benefit until then, Chavez said.
Flu symptoms include fever, cough, sore throat, a runny or stuffy nose, muscle or body aches, headaches and fatigue.
Chavez said viruses other than H1N1 can also cause those symptoms, but a high fever and bad cough indicate influenza infection.
People can stop the spread of flu by limiting contact with others when ill, covering their nose and mouth when coughing or sneezing, washing hands thoroughly with soap and water or using an alcohol-based rub, and avoiding touching the eyes, nose and mouth.
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