Respiratory tract infections (RTIs) are the most frequent infections in hum
ans, particularly in children. In addition to intervention, increasing inte
rest is focusing on immunomodulatory therapy for recurrent RTIs, which indi
cate a reduced defense capacity of the respiratory mucosa. LW 50020, an ora
l immunomodulator that contains the antigens of seven bacteria common in RT
Is, has reduced the number, duration, and severity of RTIs in children and
adults. This 56-week placebo-controlled, double-blind study in 188 children
investigated whether the efficacy of the standard schedule (immunization c
ycle + one booster cycle) would be enhanced by additional booster cycles. E
fficacy and safety over the long term were also assessed. The rate of infec
tion was reduced by 50% with the standard schedule and could not be further
decreased by two consecutive booster cycles. With both schedules, this red
uction was sustained during a 28-week treatment-free observation period tha
t followed the 28-week treatment period. The number of adverse drug reactio
ns was low, and all were transient, expected, and nonserious. These results
confirm that LW 50020 is an effective and safe strategy for RTIs.