The PARADIGM of Influenza Vaccination in Heart Failure Patients.

SEE PAGE 152 A nnual seasonal influenza epidemics of variable severity are associated with substantial morbidity and mortality worldwide, with influenza activity peaking during corresponding winter months in temperate climates of the northern and southern hemispheres (1). In the tropics and subtropics, influenza activity occurs year-round, with differences in peak periods. Most influenza disease burden estimates are derived from studies conducted in developed countries. Certain populations are considered to be at increased risk for influenza complications, including infants, the elderly, immunosuppressed persons, pregnant women, and persons with chronic conditions including pulmonary and cardiac disease (2). Prevention of influenza in the United States is focused upon annual influenza vaccination of all persons $6 months of age, although recommended target populations and different kinds of vaccines and their availability and uses differ worldwide (3). Influenza vaccine effectiveness varies by age group, immune status, and antigenic similarities between circulating influenza virus strains and vaccine strains. The World Health Organization has estimated that an estimated 3 to 5 million cases of severe influenza and approximately 250,000 to 500,000 deaths occur each year (4). Heart failure (HF) is an