An outbreak of influenza A (H3N2) in a hospital for the elderly with emphasis on pulmonary complications.

From Dec 1, 1985 to Jan 18, 1986, 133 of 379 (35.1%) mainly elderly in-patients at a hospital in Fukuoka City were infected with influenza virus A (H3N2). In 32 of the 133 (24.1%) infected with the virus, pneumonia occurred. The occurrence was significantly higher in man (33.1%) than in women (17.1%) (p less than 0.05), and the same occurrence was found to be higher in bed-ridden patients (32.7%) than in ambulatory patients (17.3%) (p less than 0.05). It was also higher in those age 70 or older (25.4%) than in those 69 years or younger (17.4%), but with no statistical difference. Seven men and one woman, all 70 years old or older, infected with the virus died of pneumonia. The overall case-fatality ratio was 6.0%. Thus, male bed-ridden patients aged 70 years or older are highly vulnerable to pneumonia in case of infection with influenza virus A.