Controlled Trial of BCG Vaccination in a School Population: Tuberculosis Studies in Muscogee County, Ga.

Abstract

In April 1947, a controlled trial of BCG vaccination was initiated in the school population of Muscogee County, Ga. Tuberculin tests with 5 T.U. of PPD were completed for 11,262 children. Non-reactors were tested with 100 T.U., and nonreactors to both doses were divided into two similar groups, one vaccinated with BCG and the other left un-vaccinated as controls. In the ensuing 12 years, there were only 35 definite cases of tuberculosis, 24 among 5-T.U. reactors, 2 among 5-T.U. nonreactors who were not tested with 100 T.U., 5 among 100-T.U. reactors, and 2 each among controls and vaccinees. The average annual case rate for 5-T.U. reactors was 134 per 100,000; for nonreactors it was only 9 per 100,000. For both controls and vaccinees, the rate was 7 per 100,000. In this area of low tuberculosis infection rates, it was not possible to demonstrate any benefit from BCG vaccination. There was a marked correlation of the tuberculosis case rate with size of reaction to the 5-T.U. dose, ranging from 8 per 100,000 among those with no induration of 199 among those with 10 millimeters or more of induration. The latter group comprised only 7 percent of the study population, but supplied 80 percent of the cases during the first 5 years of observation.