The annual toll of influenza has risen dramatically since the late 1970s, according to an analysis of U.S. death statistics. One major factor is the advancing average age of the population. Another is the increasing prevalence of virulent strains of the flu virus.
Influenza is typically not a direct cause of death, but researchers at the Centers for Disease Control and Prevention in Atlanta, estimated the disease’s contribution to mortality by noting seasonal fluctuations in deaths that might have resulted from underlying flu infections.
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