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 (Banas & Rains, 2010, p. 285). Recent research has studied the presence and function of word-of-mouth communication, or post-inoculation talk (see Compton & Pfau, 2009), following exposure to inoculation messages (e.g., Ivanov et al., 2015). Delay is the next element that is necessary in the inoculation process. There has been much debate on whether there is a certain amount of time necessary between inoculation and further attacks on a persons' attitude that will be most effective in strengthening that person's attitude. McGuire (1961) suggested that delay was necessary strengthening a person's attitude and since then many scholars have found evidence