LONG-TERM RESULTS OF BCG VACCINATION IN SOUTHERN UNITED STATES

Abstract

In 1950, a controlled trial of BCG vaccination was done in Muscogee County, Georgia, and in Russell County, Alabama. A total of 64,136 persons were included in the study population, almost all of whom were over the age of 5 years. All had satisfactory tests with 5 TU of RT 19-21, normal chest photofluorograms, and no known history of chronic lung disease. Although 29,369 were initially classified as tuberculin reactors, only 11% of the total study population is now estimated to have been infected with Mvcobacterium tuberculosis. Approximately half of the initial nonreactors to tuberculin were vaccinated. Throughout the 14 years of observation, almost three-fourths of the tuberculosis problem arose among the group of initial reactors who were not eligible for vaccination. Among the nonreactors, vaccination accounted for a reduction in tuberculosis of only 14%. The net reduction in the entire study population was thus less than 5%. The slight contribution made by vaccination was manifested almost entirely during the 1st 4 years of the trial. It was least effective among the subgroups with the highest case rates. Although tuberculosis appeared to be most common among persons with small amounts of subcutaneous fat and those in inadequate housing, there was no indication that either of these factors could account for the lack of effectiveness of BCG vaccination.