BCG vaccine extensively used even in countries where efficacy against pulmonary tuberculosis is negligible. A number of possible reasons for the variable efficacy of BCG in different countries have been proposed. None have been proven, some have been disproved, and none can explain the lack of efficacy in both low-TB burden countries (US) and high-TB burden countries (India). The reasons for variable efficacy have been discussed at length in a WHO document on BCG. BCG has protective effects against some non-tuberculosis mycobacteria. BCG has been one of the most successful immunotherapies. BCG vaccine has been the "standard of care for patients with
Inoculation theory body to a weakened form of a virus—strong enough to trigger a response (i.e., the production of antibodies), but not so strong as to overwhelm the body's resistance. Attitudinal inoculation works the same way: Expose the receiver to weakened counterarguments, triggering a process of counterargument which confers resistance to later, stronger persuasive messages. This process works like a metaphorical vaccination: the receiver becomes immune to attacking messages that attempt to change their attitudes or beliefs regarding the initial threat. Inoculation theory suggests that if one sends out messages with weak counterarguments, an individual can build immunity to those messages and