Different Strains of Bacillus Calmette–Guérin Vaccine Have Very Different Effects on Tuberculosis and on Unrelated Infections

Bacillus Calmette–Guérin (BCG) vaccine provides good protection against dissem-inated mycobacterial diseases such as miliary tuberculosis, tuberculous menin-gitis, and leprosy [1, 2] but weaker pro-tection against pulmonary tuberculosis, especially in rural areas near the equator [3]. In high-mortality countries, until a different vaccine is given, BCG vaccine also provides nonspecific (heterologous) protection against diseases other than tuberculosis and leprosy (mainly res-piratory infections and sepsis) [4]. In randomized trials in Guinea-Bissau, vaccination with BCG–Danish vaccin