In 1936 Bull and Rankin1 reported the results of vaccination against smallpox in 5,000 college students at Lehigh University, Bethlehem, Pa. From their results they estimate that more than thirty-three out of each thousand American students entering college have never been vaccinated for smallpox and further that seventy-five out of each thousand college students are without adequate protection against smallpox.
In the same year a more extensive survey was reported by Collins.2 This survey includes studies of the rural, urban and metropolitan general white population of the United States and records data on the history and frequency of vaccination against smallpox in 9,000 families. Collins found that approximately 70 per cent of the adults had a positive history of vaccination or had had smallpox at some time. Of this 70 per cent, 65 per cent had been vaccinated. This survey showed that there was a larger percentage of