Influenza Surveillance – United States, 1992-93 and 1993-94
Influenza remains a cause of substantial morbidity and mortality in the United States (1). During influenza epidemics, visits to physicians, clinics, and emergency rooms, as well as hospitalizations caused by influenza-related complications, may increase. Persons greater than or equal to 65 years of age and those with underlying chronic health conditions, including cardiovascular disease, pulmonary disease, and certain metabolic conditions are at increased risk for complications of influenza infection and are more likely than the general population to be hospitalized if infected. During major epidemics, hospitalization rates among the elderly and persons who have underlying chronic health problems may increase twofold to fivefold compared with nonepidemic periods (2). Influenza epidemics also are associated with increased mortality. Since 1968-69, the influenza virus subtype generally associated with the highest mortality has been influenza A(H3N2). During nine of 20 influenza seasons (from 1972-73 through 1991-92), greater than 20,000 influenza-associated excess deaths occurred each season; during four of these seasons, greater than 40,000 deaths occurred (CDC, unpublished data). Although there is season-to-season variability, in recent years greater than 90% of influenza-associated deaths have occurred among persons greater than or equal to 65 years of age (3).
https://www.cdc.gov/mmwr/preview/mmwrhtml/00046025.htm