Dr. Ron Chapman, director of the California Department of Public Health and state health officer, said six of the 278 were pediatric deaths. There are an additional 29 deaths under investigation, but not yet confirmed, he said.
The deaths were highest in Fresno, 21; San Diego, 23; Sacramento, 25; and Los Angeles, 36.
In all of the 2012/2013 season, a total of 106 deaths were reported.
The great majority of reported influenza deaths in persons age 65 and younger have occurred in people with underlying medical conditions. Both outpatient visits and hospitalizations continue to decrease. The influenza season status remains widespread.
"Even a single death from the flu is a tragedy," Chapman said in a statement. "The best way to prevent influenza is by getting vaccinated."