The idea of isoniazid chemoprophylaxis was first conceived over 30 years ago by a group of workers in the Public Health Service led by the late Dr Carrol Palmer. A series of excellently conducted trials followed, directed by Drs Shirley Ferebee Wolpert and George Comstock, showing that isoniazid prophylaxis reduces morbidity from tuberculosis by some 50% to 80% in individuals who took the drug for a period of 12 months.1
We realized at that time that in North America the stage had been reached where the majority (perhaps as many as 80%) of all the cases of active tuberculosis were arising as a result of remotely acquired infection in persons infected many years, often a number of decades, previously.2 We estimated that if these previously infected tuberculin-positive individuals would take isoniazid for one year, we could reduce tuberculosis morbidity in North America by at least half.
Grzybowski S. Isoniazid Chemoprophylaxis. JAMA. 1986;255(12):1615. doi:10.1001/jama.1986.03370120093030