Can multiple doses of BCG vaccine protect against asthma?

OBJECTIVE To compare BCG vaccination involving a single intradermal dose and that involving multiple doses, one given with the multiple puncture technique, in terms of the protective effect against the subsequent onset of asthma. METHODS A retrospective cohort study involving 2,311 individuals having received the BCG vaccine. The patients were classified according to the number of doses of BCG vaccine administered (one; two; or three or more). The minimum follow-up period in order to determine whether there was any protective effect of BCG vaccination regarding the diagnosis of asthma was 10 years. RESULTS The sample included 1,317 individuals (56.99%) who had received only one BCG dose, 644 (27.87%) who had received two doses, and 350 (15.14%) who had received three or more doses. The number of patients diagnosed with asthma among those who had received one dose, two doses and three or more doses was, respectively, 216 (16.40%), 107 (16.61%) and 50 (14.28%). There were no significant differences among the groups. CONCLUSIONS In the study sample, the prevalence of asthma among individuals having received multiple doses of the BCG vaccine was no different than that observed among those having received a single dose.