Background: This study was conducted to assess the efficacy of OM-85 BV (Broncho-Vaxom) in the prevention of pediatric recurrent respiratory tract infections (RTIs). Available evidence suggests that defining recurrent RTIs as ≥3 infections per fall-winter semester is both medically and epidemiologically justified. Therefore, this criterion was chosen as a primary endpoint. Methods: Trials were identified through consultation of bibliographic databases and other channels. Eleven non-blinded studies plus one dealing with primary prevention were excluded and eight randomized controlled trials were included in the meta-analysis. The data were compared at 6 months, which represented the end of most studies. The complete database was examined according to the guidelines of the Cochrane collaboration. Results: The mean age of children and the number of RTIs in the preceding year were comparable at admission. Of the patients in the OM-85 BV treated population (n=435), 32% had recurrent RTIs (that is, ≥3 RTIs/6 months) vs. 58.2% in the placebo treated population (n=416; P<0.001). Sensitivity analysis showed that this was not driven by any particular trial. The results of this review were also positive for the active treatment regarding the secondary variables, which were represented by the number of patients with at least one RTI and the mean number of RTIs. Conclusions: This meta-analysis shows, as observed in several individual trials, that the population treated with OM-85 BV had significantly and consistently fewer cases of recurrent RTIs. The data suggest that the effect is greater in patients at increased risk of recurrent RTI
