BCG-associated heterologous immunity, a historical perspective: intervention studies in animal models of infectious diseases

Abstract

The WHO Special Advisory Group of Experts (SAGE) review of the available epidemiological and trial evidence in humans concluded that bacillus Calmette-Guérin (BCG) vaccination leads to beneficial heterologous ('non-specific') effects, specifically on all-cause mortality. Randomized controlled trials showing this beneficial effect suggest improved survival is the result of enhanced protection against infection. This paper reviews the available evidence for the attenuating effects of BCG vaccine on experimental infections in animal models, including protection from bacteria, viruses, parasites and fungi. The reviewed studies suggest that BCG activates multiple immune pathways and that the basi..