BCG vaccine 400 per 100,000 in that higher risk context). The age of the person and the frequency with which BCG is given has always varied from country to country. BCG is prepared from a strain of the attenuated (virulence-reduced) live bovine tuberculosis bacillus, "Mycobacterium bovis", that has lost its ability to cause disease in humans. Because the living bacilli evolve to make the best use of available nutrients, they become less well-adapted to human blood and can no longer induce disease when introduced into a human host. Still, they are similar enough to their wild ancestors to provide some degree of
Inoculation theory opinion. These contexts include: politics (e.g., Pfau et al., 1990; see Compton & Ivanov, 2013, for a review), health campaigns (e.g., Pfau & VanBockern, 1994; see Compton, Jackson, & Dimmock, 2016, for a review), marketing (e.g., Compton & Pfau, 2004) and education (Compton, 2011), among others. (See Banas & Rains, 2010, for a meta-analysis, and Compton, 2013, for a narrative overview.) The inoculation process is analogous to the medical inoculation process from which it draws its name; the analogy served as the inaugural exemplar for how inoculation confers resistance. As McGuire (1961) initially explained, medical inoculation works by exposing the