The standard therapeutic strategy for bacterial episodes (and bacterial superinfections) is the repeated use of antibiotics. Although antibiotics are fast acting and curative, they do not prevent recurrence or complications. The incidence of recurrent respiratory infections and a substantial increase of costs justify preventive measures based on boosting the patients' immune system by immunomodulation using bacterial products, which, in the long term, stimulates immunity and reduces recurrence of infection. This study was designed to review the epidemiological features of respiratory infections and prevention strategies in adults. A narrative review was performed of the relevant literature. Several products of the immune modulator class are available: bacterial lysates, bacterial membrane component by-products, chemically synthesized compounds, and specific bacterial components (ribosome-component immune modulator [RCIM]). The clinical efficacy of the RCIM has specific and nonspecific immunostimulant properties. Efficacy is mainly documented by decreased recurrent episodes of infection and prescription and need for antibiotics. Benefits are generally observed after 3 months of treatment and are maintained for 6 months. Clinical trial evidence is accruing of the efficacy of RCIM in preventing recurrence of upper and lower airway infections or relapses in adults.