SACRAMENTO, California (Reuters) - An unusually severe flu season has claimed the lives of at least 147 young and middle-aged people in California - 10 times the number killed by influenza viruses by the same time last year, public health officials said on Friday.
The California deaths were caused by a strain of the influenza virus that is sending sufferers across the nation to the doctor for flu-like symptoms at rates that are 50 percent higher than normal, said Lyn Finelli, head of the influenza surveillance and outbreak response team at the Centers for Disease Control and Prevention.
"That's way above the norm for flu," Finelli said. "It tells us we're still in the middle of flu season, and in the Northeast and California it's going up, up, up."
The flu strain responsible for the California deaths, H1N1, also predominates nationwide this year. It hits people hardest between the ages of 25 and 64, partly because some older people are believed to have more immunity due to similar outbreaks many decades ago.
In California, 52 people died last week alone, including one child, the state's chief of communicable disease control told reporters on a conference call Friday.
"This influenza season continues to be a severe one as the increasing number of influenza-related deaths indicates," Ron Chapman, director of the California Department of Public Health, said in a statement, urging Californians to get vaccinated.
In addition to the 147 confirmed California flu-related fatalities this season among people under age 65, another 44 suspected flu deaths remain under investigation, said Dr. James Watt, chief of the state's Division of Communicable Disease Control. Most of those felled by the disease had other health conditions, but not all, he said.
Last year at the same time, the state had recorded just 14 flu deaths among Californians under age 65.
The death of a 47-year-old television advertising executive in the state's capital city prompted a renewed call for residents to become vaccinated against flu. Sacramento County, with 21 deaths so far, leads the state in fatalities.
"After reading the heartbreaking story of Nancy Pinnella, went to CVS and got my first flu shot ever," California's first lady, Anne Gust Brown, posted on Twitter.
It is not fully clear whether California is an outlier in the severity of its cases, because states are not required to report flu deaths to the CDC, and data is collected differently from state to state and county to county, said CDC spokesman Jason McDonald.
The fatality data that the public health agency does collect, on pediatric deaths, is not useful in studying H1N1, because the virus is more likely to attack adults, Finelli said.
The public health agency does, however collect information on why people go to the doctor, and whether they are hospitalized for flu. Those signs, she said, show that this year's flu is likely to continue to hit hard.
Although the number of cases nationwide appears to have plateaued, she said, that does not take into account that California and the Northeast are lagging other areas with a late flu season.
Meanwhile, CDC data does show that far more people under the age of 65 are being hospitalized with flu-like symptoms than last year. As of last week, for example, 76 percent of those hospitalized for flu were under age 65, compared to less than 50 percent last year.
Nationwide, the data shows that somewhat fewer people have contracted flu so far this year than last year, Finelli said. This year's strain, however, appears to be causing severe illness in a population that is more typically robust, she said.
Reporting by Sharon Bernstein; Editing by Cynthia Johnston and Lisa Shumaker