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 Inoculation The terms inoculation, vaccination, and immunization are often used synonymously to refer to artificial induction of immunity against various infectious diseases. However, there are some important historical and current differences. In English medicine, inoculation referred only to the practice of variolation until the very early 1800s. When Edward Jenner introduced smallpox vaccine in 1798, this was initially called cowpox inoculation or vaccine inoculation. Soon, to avoid confusion, smallpox inoculation continued to be referred to as variolation (from "variola" = smallpox) and cowpox inoculation was referred to as vaccination (from Jenner's use of "variolae vaccinae" = smallpox of the cow).