In 1921, the BCG vaccine was first administered to humans, marking a significant milestone in the medical effort to combat tuberculosis. Developed from a weakened strain of bovine tuberculosis bacteria, the vaccine was designed to provide protection against the disease, which at the time remained a leading cause of mortality worldwide. Its introduction represented the culmination of years of research into immunology and the pursuit of a reliable prophylactic measure against a persistent and often fatal respiratory infection.

The implementation of the vaccine proved particularly effective in preventing severe, disseminated forms of tuberculosis in infants and young children, such as tuberculous meningitis and miliary tuberculosis. By stimulating the immune system to recognise and defend against the pathogen, the vaccine became a cornerstone of public health strategies in many nations. Its deployment was tailored to reflect local epidemiological conditions, with various countries adopting different policies regarding universal or targeted immunisation programmes based on their specific risk profiles.

Throughout the twentieth century and into the present day, the BCG vaccine has remained a vital component of the global strategy to manage and control tuberculosis. While its efficacy in preventing pulmonary tuberculosis in adults has been shown to vary, its continued use underscores the ongoing international commitment to reducing the burden of the disease. The vaccine serves as a testament to the progress made in the field of immunology and the enduring importance of preventative medicine in safeguarding public health.

• First administered to humans in 1921.
• Developed to provide protection against tuberculosis.
• Highly effective at preventing severe childhood forms of the disease.
• Adopted globally according to varying national risk profiles.
• Remains a central element of modern tuberculosis control efforts.