Pneumonia and influenza deaths during epidemics: implications for prevention.

Pneumonia and influenza (P&I) deaths among adults during epidemics of influenza A (H3N2) virus are reviewed and risks of such deaths according to age and presence of chronic disease are estimated from medical records of a large group practice. Thirty-eight deaths occurred among 310 persons hospitalized with P&I. Flu-like symptoms occurred in 30 patients (79%), 26 patients (68%) were older than 65 years, 36 patients (95%) had chronic disease, and approximately half were medically stable before the terminal episode. These values were similar to those of P&I deaths during nonepidemic periods. Pneumonia and influenza death rates ranged from fewer than ten to more than 600 per 100,000 among healthy vs chronically ill adults. Highest rates (870 per 100,000) occurred in persons with both cardiovascular and pulmonary disease. Application of these findings to influenza vaccination strategies in clinical practice is discussed.