BCG vaccine fine powder. Sometimes the powder is sealed with vacuum in a glass ampoule. Such a glass ampoule has to be opened slowly to prevent the airflow from blowing out the powder. Then the powder has to be diluted with saline water before injecting. The history of BCG is tied to that of smallpox. Jean Antoine Villemin first recognized bovine tuberculosis in 1854 and transmitted it, and Robert Koch first distinguished "Mycobacterium bovis" from "Mycobacterium tuberculosis". Following the success of vaccination in preventing smallpox, established during the 18th century, scientists thought to find a corollary in tuberculosis by drawing a parallel
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