Simple, practical ways to assess the protective efficacy of a new tuberculosis vaccine.

There is strong evidence that tuberculin sensitivity cannot be used to evaluate the efficacy of different strains of bacille Calmette-Guérin (BCG). For identifying efficacious strains of BCG and evaluating candidates for new vaccines, the best method is a randomized trial. Simple trials in which newborns would be vaccinated with new and old vaccines in alternate years could demonstrate which vaccine was the better.