The agency said those who died ranged in age from 35 to 80 years old and all had underlying medical conditions.
Last season, 65 flu-related deaths were reported in the county.
For the week ended Jan. 11, the agency reported 677 lab-confirmed influenza cases, versus 361 previous week. Total confirmed cases this season now stand at 1,391.
The predominant influenza virus in San Diego this season is Pandemic H1N1. Compared to last season, a significantly higher proportion of young and middle-aged adults are being reported with flu, which is expected with H1N1.
County health officials are encouraging everyone to get immunized.
"Although influenza activity in San Diego has greatly increased over the past month, it’s not too late to get immunized. The vaccine is the best protection against the flu," said Wilma Wooten, the county's public health officer.
"Influenza can be a serious and deadly disease, especially for the elderly and young infants, as well as for people with chronic conditions like heart disease or diabetes."
In addition to getting vaccinated, the county advises the following steps to avoid getting sick:
- Wash hands thoroughly and often
- Use hand sanitizers
- Stay away from sick people
- Avoid touching your eyes, nose, and mouth
- Clean commonly touched surfaces
- If you are sick, stay home and avoid contact with others