BCG vaccine--current status.

Tuberculosis incidence has made re-emergence due to multidrug resistance of the bacilli and for acquired immunodeficiency syndrome. Of all vaccines BCG is most widely used. It protects children from secondary forms of tuberculosis. Several authors recommend a second dose to boost the waning effect of BCG. The vaccine at present needs to be improved to make it more efficacious. Vaccines which involve the protective immune responses are ideal.