Each year, tuberculosis strikes about nine million people worldwide; about two million die from the persistent infection. The disease is becoming deadlier as more strains of the TB bacterium develop resistance to the drugs used to treat it. And the only vaccine against TB, derived from the TB bacteria that infect cows, is often ineffective: in recent tests, the vaccine protected fewer than half of those immunized.

Immunologist William Jacobs and his coworkers at New York's Albert Einstein College of Medicine may have found a way to fortify our crumbling defenses against TB. Jacobs has created a vaccine based on the TB bacterium that infects humans; by using mutant strains of the bacterium, he has made a vaccine that he describes as safe yet far more effective than ones based on the cow TB bacteria. Jacobs hopes to have the vaccine in clinical trials within a year.