BCG vaccine screened for active tuberculosis. BCG is also contraindicated in certain people who have IL-12 receptor pathway defects. BCG is given as a single intradermal injection at the insertion of the deltoid. If BCG is accidentally given subcutaneously, then a local abscess may form (a "BCG-oma") that can sometimes ulcerate, and may require treatment with antibiotics immediately, otherwise without treatment it could spread the infection causing severe damage to vital organs. However, it is important to note an abscess is not always associated with incorrect administration, and it is one of the more common complications that can occur with the vaccination.
Inoculation a 20% incidence of severe scarring), many parents felt that the benefits of inoculation outweighed the risks and so inoculated their children. Two forms of the disease of smallpox were recognised, now known to be due to two strains of the Variola virus. Those contracting "Variola minor" had a greatly reduced risk of death – 1–2% – compared to those contracting "Variola major" with 30% mortality. Infection via inhaled viral particles in droplets spread the infection more widely than the deliberate infection through a small skin wound. The smaller, localised infection is adequate to stimulate the immune system to produce