Increases in mortality from pneumonia and high-risk chronic diseases have not occurred during recent influenza epidemics. Excess mortality during the past four influenza epidemics in the United States is attributable to influenza reported as a primary cause of death, and the average excess was only about 4,000 deaths per epidemic. Most clinical influenza severe enough to cause hundreds of millions of days of bed disability during nonepidemic as well as epidemic years is not caused by the influenza viruses. During the nonepidemic year of 1973 to 1974, there were 61,841,000 episodes of clinical influenza severe enough to put people to bed for an average of 3.6 days. In my judgment there is now no basis for recommending annual administration of influenza vaccines to so-called high-risk groups and persons over 64 years of age.
(JAMA 237:2823-2828, 1977)
Sabin AB. Mortality From Pneumonia and Risk Conditions During Influenza EpidemicsHigh Influenza Morbidity During Nonepidemic Years. JAMA. 1977;237(26):2823-2828. doi:10.1001/jama.1977.03270530031018