PROPHYLACTIC IMMUNIZATION OR VACCINATION 669 



it was not until Edward Jenner made his investigations into a theory 

 held by farmers and by experimental evidence established it as true that 

 a satisfactory method of immunizing the body against smallpox was 

 introduced. 



The peasantry in various parts of Europe, and especially in England, 

 had generally observed that those who had had sores on their hands con- 

 tracted from similar lesions on the teats of cows, usually escaped small- 

 pox infection when the disease was epidemic in a community. In fact, 

 it is said that several farmers deliberately inoculated members of their 

 family with cowpox lesions and that these escaped smallpox. 



Edward Jenner was a physician practising in Berkeley, Gloucester- 

 shire, and frequently used the method of direct inoculation from a mild 

 case of smallpox among his patients. While a student he was impressed 

 with the traditions of cowpox vaccination, and finding that they were 

 largely true, determined to make experimental tests. On May 14, 

 1796, he vaccinated a boy, James Phipps, with virus from a cowpox 

 lesion on the hand of a dairy maid, Sarah Nehnes, and on July 1st he 

 inoculated the same boy with pus from a smallpox patient without re- 

 sulting infection. In 1798 he furnished further proof that cowpox will 

 afford protection against smallpox by inoculating a child direct from a 

 vesicle on the teat of a cow, and continued the inoculation from arm to 

 arm through a series of five children, after which all were inoculated 

 with smallpox virus, without a single case developing. In the same year 

 he published "An Inquiry into the Causes and Effects of the Variolse 

 Vaccinae," illustrated by four plates, and within a year or two vaccina- 

 tion became general over Europe. 



Vaccination was introduced into the United States in July, 1800, by 

 Dr. Benjamin Waterhouse, Professor of Physic at Harvard University, 

 who vaccinated his own children. At about the same time John Red- 

 man Coxe, of Philadelphia, vaccinated his oldest child and then tested 

 the experiment by exposing him to cases of smallpox. This bold repeti- 

 tion of Jenner 's experiment considerably strengthened public confidence 

 in the method and the practice spread rapidly. Thomas Jefferson, writ- 

 ing in 1806 to Edward Jenner, said: "Future generations will know by 

 history only that the loathsome smallpox existed and by you has been 

 extirpated." 



But 'Jenner and his earlier supporters met with much opposition, 

 often bitter and unrelenting, and this is readily understood when it is 

 realized that even at the present day, over a hundred years later, cow- 

 pox vaccination still has its opponents, in spite of the fact that the 



