BCG Re-vaccination for Primary Tuberculosis Prophylaxis in the Prison Population

In the last decade, the incidence of tuberculosis (TB) has declined in much of the world, but has increased in Central and South America. Since 2000, the prison population in these localizations has grown by 206%, the highest increase in the world. In the same period, the reported cases of TB among the prison population (PP) increased by 269%. The extraordinarily high risk of acquiring TB within prisons creates a health and human rights crisis for PP that also undermines broader TB control efforts. Same studies identified an annual incidence of 26,000 per 100,000 for latent TB infection (through conversion of the tuberculin skin test) and of 4,000 per 100,000 for active TB among the PP in the state of Mato Grosso do Sul. In view of the combination of a high rate of infection and development of active disease and a short period of incarceration (on average 3 years), primary prophylaxis with BCG revaccination may be a cost-effective alternative associated with mass screening for control of the disease. Recently, in a phase 2 clinical trial, the BCG vaccine was shown to be 45% effective in preventing sustained IGRA conversion in adolescents in South Africa. With this study, the investigators aim to evaluate the effectiveness of BCG revaccination for primary TB prophylaxis in healthy individuals exposed to an environment of high disease transmission. This is an open-label, randomized phase IV clinical trial involving 760 individuals from three prisons in the state of Mato Grosso do Sul. Participants will be monitored for 26 months to calculate vaccination effectiveness to reduce latent tuberculosis infection as measured through sustained IGRA conversion. By carrying out this clinical trial, the researchers intend to obtain scientific evidence that can contribute to the tuberculosis control policy in Brazil.