A 40-year-old San Jose mother of three died only two days after coming down with the flu, according to news reports.

A service attended by 500 mourners was held over the weekend for Katie Denise Oxley Thomas, one of 42 Californians under 65 who have died from the disease since flu season began Oct. 1, state health officials say.

Most of the victims have been adults, and most (70 percent) haven't been vaccinated, officials say.

Thomas' death on Jan. 4 stunned her family. How could this happen to a robust, athletic woman who liked to run marathons?

"I can tell you that she seemed absolutely fine on New Year's Eve and called a friend Tuesday morning saying she had a sore throat, and by Wednesday she was in the ICU," her sister, Amber, told the San Jose Mercury News.

According to her family, Thomas also came down with a fever and achey symptoms in addition to the sore throat on a Tuesday. A trip to the doctor confirmed she had the flu, and rest at home was prescribed.

But the next day, her symptoms worsened, so she went to Good Samaritan Hospital's emergency room. Again she was told she had the flu and advised to go home.

By Wednesday night, she was having trouble breathing, so her boyfriend drove her back to the ER. She was admitted with pneumonia and put on a ventilator.

By Thursday morning she had gone into septic shock. Fever soon overwhelmed her system. Doctors desperately tried to stabilize her, but nothing worked. She died at about 5 p.m.

Thomas' brother, Anthony Oxley, believed she had gotten a flu shot, but was not sure.

"I would definitely tell people to get the flu shot," he told the Mercury News. "I know it might not keep you from getting the flu, but it might keep you from dying from it."

Of the 42 California deaths attributed to the flu in the latest count Friday, 19 have been in the greater Bay Area, including six in Contra Costa County and five in Santa Clara County.

Only three days earlier, the state tally stood at 27 flu-related deaths.

Flu-related deaths are well above normal for this time of year, according to a report by Erin Allday in the San Francisco Chronicle. So are hospitalizations and doctor visits for the flu, and public health officials fear it could shape up to be the worst flu season in a decade.