Influenza is a leading cause of morbidity and mortality in patients with chronic respiratory diseases. This study compares two influenza prevention schemes in patients with chronic obstructive pulmonary disease and chronic asthma. We enrolled 66 patients, distributed as follows: Group A: 32 subjects treated with influenza vaccine; Group B: 34 patients treated with influenza vaccine and bacterial immunostimulant. The rate of influenza episodes was recorded. Hemoagglutination inhibiting antibody titers for vaccine strains H1N1, H3N2, and B were determined at time 0 (prior to vaccination), and on days 30 and 90 following vaccination. We observed a lower rate of influenza episodes in Group B patients (8.82%) compared to Group A (31.25%) (p < 0.05). At day 90 Group B patients presented higher geometric mean antibody titers for strains H1N1 (p = 0.07) and H3N2 (p = 0.08). Bacterial immunostimulants appear as possible adjuvants in the prevention of influenza episodes, and may prolong antibody response to influenza vaccine strains.