If tubercle bacilli can float through the air and cause disease in people who inhale them, why cannot weakened bacilli be transmitted the same way to achieve mass vaccination? This was the question that Dr. Gardner Middlebrook and colleagues at Denver's research-wise National Jewish Hospital asked themselves. Last week, after years of testing, they gave the National Tuberculosis Association a tentative answer: no reason why not.
Dr. Middlebrook and Dr. Maurice Cohn put more than 1,000 guinea pigs into chambers rigged so that the ventilators blew in BCGBacillus of Calmette and Guerin, a strain of weakened microbes used in vaccination against tuberculosis (TIME, Sept. 23, 1957). Later exposed to virulent TB germs, these animals resisted disease and lived out their normal life span. Those in an untreated comparison group sickened and died. Follow-up tests by Dr. Sol Roy Rosenthal at the University of Illinois showed that BCG, wafted in 10 million times its own volume of air, "took" in 27 of 30 children and young adults, who are now believed to have a high degree of immunity against TB, though it cannot be proved.
If its apparent effectiveness is confirmed, airborne vaccination will have a cost advantage over multiple BCG punctures in the arm, because it requires far less vaccine. And Dr. Middlebrook believes that his method will interfere less with the standard tuberculin skin test for TB infection. Obscured results in this test have been a major factor in U.S. opposition to wide use of BCG, though the N.T.A. convention heard from Northwestern University's Dr. Guy Youmans last week about a cheap, simple blood test which may reinforce and partly replace the tuberculin test. Most important to Dr. Middlebrook is the simplicity of his proposed airborne vaccination: "It would be easy to immunize a theater full of children while they were watching a Mickey Mouse cartoon."