New vaccines against tuberculosis: lessons learned from BCG immunisation in Brazil.

The current tuberculosis (TB) vaccine Mycobacterium bovis BCG has been employed for some 70 years in Brazil and lessons from its use should be taken in account for the development or improvement of new TB vaccines. The vast majority of the current population has been vaccinated with BCG, with the possible requirement for a booster immunisation in adulthood for TB protection. BCG Moreau strain also protects against leprosy, meningitis and extrapulmonary forms of TB. Factors related to differences in strain, dosage and BCG administering protocol have been responsible for the variable efficacy of BCG. This vaccine is clearly affected by, as yet unclear, host and/or environmental variables. In this brief review, we describe some aspects of BCG immunisation observed in Brazil that may be of importance for improving or replacing BCG.