CDC makes changes to flu death estimates

Officials with the U.S. Centers for Disease Control and Prevention have backed away from a decades-long estimate of the number of people who die annually from the flu, taking a new position that flu deaths vary widely from year to year.

CDC officials told Reuters last week that the actual number of annual flu deaths over the past 30 years has ranged from a low of approximately 3,300 deaths to a high of 49,000 deaths.

For years now, the CDC has gone with an estimate of 36,000 flu-related deaths each year, a figure usually cited in an effort to encourage people to get flu shots. The long-held 36,000 estimate was based on data from the 1990s when H3N2 viruses were active, Dr. David Shay, a medical officer with the CDC’s National Center for Immunization and Respiratory Diseases, told Reuters.

“Flu really is unpredictable,” Shay told Reuters. “We don't know what the impact of flu will be at the beginning of a particular season.”

Shay also told Reuters that the CDC’s new analysis suggests that years when H3N2 flu strains were strongest, flu-related deaths were 2.7 times higher than in years when H1N1 or influenza B viruses were prominent.

CDC officials said that, because of that variability, it is more accurate to use a range of deaths. Better diagnostic tests and improved ways of tracking flu deaths, however, will be created and implemented over time.

“Because we have this very wide range of deaths - from 3,000 to 49,000 - it's really meaningless to say what happens in an average flu season,” Shay said, according to Reuters.

One factor that has remained consistent is that the flu seems to strike the elderly the hardest. CDC officials estimate that approximately 90 percent of flu deaths in the 31 flu seasons between 1976 to 2007 occurred in people over the age of 65.

The CDC said the best way to prevent flu-related deaths is an annual flu vaccine, and recommends that virtually everyone over the age of six months gets one.