Effectiveness of BCG vaccine
The effectiveness of a vaccine means its capability to protect vaccinated people from the disease that immunization aims to prevent. In the case of BCG vaccine, the effectiveness is highly variable — protection from TB ranges from 0–80% of those who are vaccinated. This means that some vaccinated individuals may not be protected against TB at all, and up to 80% of the others will receive some protection. The strongest reason for vaccinating with BCG is that it protects young children against developing the more serious forms of tuberculosis, such as TB meningitis (affecting the brain), TB in both lungs and extra-pulmonary TB (affecting other organs).