The number of people hospitalized in the United States because of the flu has climbed substantially over the past two decades to an average of more than 200,000 a year, in large part because of the aging of the population, a government study found.
Severe cases of the flu can result in pneumonia, dehydration or a worsening of chronic medical conditions, and can be life-threatening — especially for the very old or the very young.
Coming just as doctors are receiving the first supplies of this year’s flu vaccine, the study demonstrates that the ailment is not trivial, and underscores the importance of prevention, said lead researcher William Thompson of the Centers for Disease Control and Prevention.
The annual average of 226,054 hospitalizations a year is almost double the CDC’s previous estimate, partly because it includes data from more recent years when more severe virus strains prevailed, and partly because the researchers used a broader category of flu-related illnesses to reach the new estimate.
The findings were published in Wednesday’s Journal of the American Medical Association.
The study “is yet another clear, solid argument for people to get themselves vaccinated, and it couldn’t come at a more important time,” said Dr. William Schaffner, a flu expert at Vanderbilt University.
The nationally representative findings are based on records from about 500 hospitals from 1979 through 2001.
Annual flu shots recommended
In the first flu season examined, 1979-80, there were 120,929 flu-related hospitalizations. Though the number was lower in some subsequent years, the overall trend was an increase, and by 1999-2000, there were 426,662 hospitalizations. That year, the prevailing virus was H3N2, a particularly powerful form.
Other forms dominated in 2000-01, when there were 170,899 flu-related hospitalizations.
The CDC has no nationwide totals on hospitalizations or deaths from last year’s flu season, which raised alarm by causing several early deaths in children but ended up being fairly typical.
The study found that after age 49, the risk of flu-related hospitalization increased with advancing age. The highest number of hospitalizations was in people 85 and older, averaging 40,813 yearly.
The researchers noted that between 1976 and 2001, the number of U.S. citizens 85 and older more than doubled.
A CDC report last year found the number of flu-related deaths surged fourfold from 1976-77 to 1998-99 and now averages about 36,000 a year.
Annual flu shots have been recommended for people 65 and older since the 1960s and for those 50 and older since 2000, but only about two thirds of older adults get vaccinated.
Annual shots also are recommended for all children ages 6 months to 23 months; women who will be pregnant during flu season; and people with chronic health problems including heart disease, diabetes and asthma.