A randomized, placebo-controlled, double-blinded, single-centre, phase IV trial to assess the efficacy and safety of OM-85 in children suffering from recurrent respiratory tract infections.

Background: Over many years, OM-85, a lysate of 21 common bacterial respiratory pathogens, has been demonstrated to prevent respiratory recurrences in children. However, further studies are needed to explore the true importance of OM-85 in the prevention of respiratory tract infections (RTIs) in children. This study was planned to further contribute to the evaluation of the role played by OM-85 in prevention of recurrent RTIs in children.

Methods: This study was a randomized (3:3:1), placebo-controlled, double-blind, single-centre, phase IV trial carried out in Italy to assess the efficacy of OM-85 (Broncho-Vaxom; Vifor Pharma; Meyrin 2/Geneva, Switzerland) in reducing the number of new RTI episodes in 288 children aged 1 to 6 years with a history of recurrent RTIs and to compare the efficacy of the standard 3-month regimen with that of administration of OM-85 for 6 months during a 6-month study period.

Results: The number of RTIs and of children who experienced at least one RTI were significantly lower among patients receiving OM-85 for 3 months than among those given placebo (33% vs 65.1%, p < 0.0001). Differences were statistically significant for upper RTIs (i.e., common cold/viral pharyngitis and acute otitis media; p < 0.0001 and p = 0.006, respectively). Days of absence from day-care for children and working days lost by parents were significantly lower in the group with children treated with OM-85 for 3 months than in the placebo group (p = 0.007 and p = 0.004, respectively). No difference was seen between children who received OM-85 for 3 and those who received OM-85 for 6 months. The prevalence of atopy as well as the history of recurrent wheezing and age of the study child did not influence the results. Benefit was maximally evident among children with a history of frequent recurrences. OM-85 was well tolerated and safe, even in children who received an influenza vaccination.

Conclusions: The use of OM-85 for 3 months in 3 series of 10 consecutive days each time reduces the risk of recurrent RTIs in children, with a favourable safety profile. The greater effect observed in children prone to several respiratory episodes than in non-prone children seems to indicate that this lysate should be administered especially to children with a proven high susceptibility to RTIs.