A controlled trial of a killed Haemophilus influenzae vaccine for prevention of acute exacerbations of chronic bronchitis.

Sixty-four patients with chronic bronchitis with a history of recurrent respiratory tract infections were admitted to a double-blind randomised controlled study in which the efficacy of an oral vaccine containing killed Haemophilus influenzae in preventing acute exacerbations of chronic bronchitis was compared with placebo. Patients given vaccine developed fewer acute infective episodes. Although the numbers of patients who required antibiotic therapy in the two groups were not significantly different, the number of antibiotic prescriptions given to the vaccinated group of patients was significantly less than that required by the control group. A reduction in colonisation with Haemophilus influenzae occurred in the active group, which was maximal 14 weeks after the onset of the study.