Effectiveness of the influenza vaccine at preventing hospitalization due to acute lower respiratory infection and exacerbation of chronic cardiopulmonary disease in Korea during 2010-2011

Abstract

Background: Influenza epidemics are accompanied by a considerable increase in hospitalization due to acute lower respiratory infection and exacerbation of underlying medical conditions. We estimated the effectiveness of the influenza vaccine at preventing hospitalization due to acute lower respiratory infection and new onset or acute exacerbation of chronic cardiopulmonary disease. Method: During the peak influenza period in 2010?2011, we performed a multicenter, case?control, retrospective cohort study of patients who were hospitalized due to newly developed pneumonia, bronchitis, and bronchiolitis, or new onset or acute exacerbation of asthma, COPD, ischemic heart disease, and CHF. Controls were selected from outpatients who visited study hospitals but who were not hospitalized during the same study period. Controls were matched 1:1 to cases based on age, gender, and date of hospital visit. Univariate and multivariate logistic regression analyses were used to determine the effectiven