The estimation of the risk of tuberculous infection from prevalence data obtained at school-age, in 1974 and in 1982, permitted the determination of the relevant trend in the city of S. Paulo, Brazil, between those years. The risk of infection decreased, on average, by 5% annually during the period. There was no evidence of any association between the proportions of vaccinated children and that of infected children among those unvaccinated, in the 59 schools studied. Tuberculin sensitivity in 7 years old school-children, vaccinated with BCG at any age between the 1st and the 6th year of life was 2.5 times more intense than that in unvaccinaetd children of the same age. With regard to the calculation of the true value of the risk of tuberculous infection, commentaries about the unrealiability of the available data were made.
Tuberculosis BCG vaccine; Tuberculin test; Hipersensibility, delayed
