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 the appropriate tools to combat the attack were more resistant than the control group. In this case, the simple act of forewarning of an attack was enough to resist the counterattitudinal persuasion. The second component, refutational preemption, is the cognitive part of the process. It is the ability to activate one's own argument for future defense and strengthen their existing attitudes through counterarguing (Pfau, 1997). Scholars have also explored whether other resistance processes might be at work, including affect. Refutational preemption provides specific content that receivers can employ to strengthen attitudes against subsequent change. This aids in the inoculation process