The scar on the arm is either the cowpox vaccine or the BCG vaccine. If you were born before 1980, the scar on your arm is the cowpox vaccine; if you were born after 1980, the scar on your arm is the BCG vaccine, which is mainly used to prevent tuberculosis. Redness, swelling, rupture and crusting of the inoculated area after BCG vaccination are normal reactions to the vaccine and there is no need for remedy. The BCG vaccine can be of great benefit to the body by enabling the body to fight tuberculosis or other TB when it is weak.