292 THE PRINCIPLES OF IMMUNOLOGY 



was 0.41 per cent. Kobe made an extensive study of the population 

 of Tokio and its suburbs. In the city of Tokio, 10.54 per cent, of the 

 entire population were vaccinated. The absolute number that were 

 vaccinated, namely, 238,936 in Tokio and 61,988 in the suburbs, as well 

 as the large number of controls, provides a sufficient number from 

 which to draw satisfactory conclusions. In Tokio cholera occurred in 

 1.85 per 10,000 of the unvaccinated and 0.13 per 10,000 among the vac- 

 cinated. In the suburbs cholera occurred in 3.09 per 10,000 of the 

 unvaccinated, and there were no cases reported among the vaccinated. 

 Cantacuzene has studied results obtained in the campaigns in the Orient 

 during the Balkan Wars and the World War. These were conducted 

 particularly during the epidemics, and by a study of the normal curve 

 of epidemics he finds that vaccination leads to a sharp drop in the 

 epidemic curve and incidence of the disease. 



Vaccination Against Pneumonia. Although vaccination against 

 pneumonia was practiced by Wright before the various types of pneu- 

 mococci had been identified, it was not until the types were carefully 

 studied that exact results could be obtained. Lister, after he had iden- 

 tified the types of organisms present in South Africa, carried out 

 prophylactic immunization in 11,000 workers in the Rand mines. He 

 employed a composite vaccine prepared from the pneumococcus types 

 prevalent in that region. He found that subcutaneous inoculations were 

 sufficient to establish an immunity, and demonstrated that the pro- 

 tection was effective against the particular type of pneumococcus used 

 in the vaccines. He emphasized the importance of using a large bulk 

 of organisms and considers that the minimum effective dose is at least 

 6000 million pneumococci of each group against which protection is 

 sought. The work of Cecil and Austin and of Cecil and Vaughan has 

 been of the utmost importance. Cecil and Austin employed a saline 

 suspension of killed pneumococci of Types I, II and III. Three or 

 four doses were given at intervals of five to seven days. The first dose 

 contained 1000 million of each of the three types; the second contained 

 2000 million of each type, and the third and fourth contained 3000 

 million each of Types I and II and 1500 million Type III. At Camp 

 Upton 12,000 troops were vaccinated, and among these only seventeen 

 cases of pneumonia of all types developed, including those due to 

 Type IV as well as to the streptococcus. Among the 20,000 unvac- 

 cinated men, 172 cases were reported. At Camp Wheeler a lipovaccine 

 was employed containing 10,000 million each of Types I, II and III per 

 cubic centimeter, given in one dose. Eighty per cent, of the total com- 

 mand, or 13,460 men, were vaccinated and 363 cases of pneumonia of all 

 varieties developed. The study was difficult because of the prevailing 

 influenza epidemic. An analysis of the records shows that " there were 

 thirty-two cases of Types I, II and III pneumonia among the vaccinated 

 four-fifths of camp, and forty-two cases of pneumonia of these types 

 among the unvaccinated one-fifth of camp. If, however, all cases of 

 pneumonia that developed within one week after vaccination are ex- 

 cluded from the vaccinated group, there remain only eight cases of 



