BCG vaccine of 2004 the vaccine is given to about 100 million children per year globally. The main use of BCG is for vaccination against tuberculosis. BCG vaccine can be administered after birth intradermally. BCG vaccination can cause a false positive Mantoux test, although a very high-grade reading is usually due to active disease. The most controversial aspect of BCG is the variable efficacy found in different clinical trials, which appears to depend on geography. Trials conducted in the UK have consistently shown a protective effect of 60 to 80%, but those conducted elsewhere have shown no protective effect, and efficacy appears
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