A 41-year-old Santa Clara County woman has died of swine flu, an ominous development that prompted health officials Friday to strongly advise people of all ages to get vaccinated.

Last year, no one in the county younger than 65 died of any flu strain.

Unlike many other flu viruses, swine flu can result in lethal pneumonia even in healthy people. Pregnant women and people who are morbidly obese are particularly vulnerable, said Dr. Sara Cody, Santa Clara County’s health officer. In 2009, about 203,000 people died worldwide in the swine flu pandemic.

“It can really be a bad actor,” Cody said. “Everyone is susceptible.”

Since flu season began in October, six other cases of severe swine flu and one case of Flu B in people younger than 65 also have been reported in Santa Clara County, the state’s sixth largest. No data was immediately available for the rest of the Bay Area.

In Orange County, a 28-year-old San Juan Capistrano woman who had an underlying medical condition died last week of H1N1.

Only flu cases that occur in people younger than 65 and that are severe enough to require hospitalization in an ICU or result in death are closely tracked by public health departments.

The Santa Clara County woman was not identified nor was the city where she lived. But the viruses are widespread, Cody said.

“We’re getting flu reported from every corner of the county,” she said.

It is not too late to get a flu shot. This year’s vaccination protects against H1N1. The shot is no guarantee of avoiding the flu, but it reduces the chances of infection.

“Use the tool we have available,” Cody said, “and get a shot.”

Residents also should cover their noses and mouths with tissues when they sneeze or cough, wash their hands often with plain soap and water or alcohol-based hand cleaners, avoid contact with those who are sick and stay home if they are sick themselves.

Contact Tracey Kaplan at 408-278-3482. Follow her on Twitter at tkaplanreport.