Two more flu deaths were reported in Contra Costa and San Mateo counties this week, health officials said.
A sixth flu death was recorded in San Mateo County this week, health officials there said Thursday.
Five of those victims had underlying medical conditions, officials said.
Additionally, five of the cases were the H1N1 strain of the flu, which is known as swine flu. Swine flu first emerged in humans in 2009 and is known to be more dangerous for young adults compared to other strains of influenza, according to health officials.
A man in his 50s succumbed to the flu in Contra Costa County, the county health department reported on Wednesday. There have been six flu-related deaths since December in that county.