Eight double-blind RCTs (851 children) were included. All studies provided an adequate description of withdrawals. Only one study provided an adequate description of randomisation. Two studies provided an adequate description of blinding.
Treatment with OM-85 BV led to a significant reduction in the proportion of children who experienced at least three respiratory tract infections over six months compared to placebo (OR 0.33, 95% CI 0.25 to 0.45, number needed to treat=4, 95% CI not reported). The proportion of children who experienced at least one respiratory tract infection was also significantly reduced (OR 0.33, 95% CI 0.23 to 0.49, number needed to treat=6, 95% CI not reported). The mean number of respiratory tract infections over six months was also significantly reduced in those treated with OM-85 BV compared to those treated with placebo (WMD -1.21, 95% CI -1.39 to -1.03). There was significant heterogeneity for all analyses. Sensitivity analysis did not alter the review findings.
The incidence of adverse events was similar in children who received placebo and OM-85 BV. There were no deaths or serious adverse events attributed or possibly attributable to the study medication.
There was no evidence of publication bias.