496 BIOLOGY OF PNEUMOCOCCUS 



tions were given at weekly intervals of a vaccine in an oil men- 

 struum containing 30 per cent of pneumococci of Types I, II, and 

 III, 40 per cent of Group IV, 20 per cent of hemolytic strepto- 

 cocci, and 10 per cent of Staphylococcus aureus, representing in- 

 dividual doses of 2.5, 5.0, and 7.5 billion cocci respectively. The 

 authors admitted that the collected data on the 93,476 individuals 

 vaccinated were far from exact ; nevertheless, the figures would 

 seem to be significant. The average incidence of influenza and pneu- 

 monia in the group receiving three injections was one-third that of 

 the incidence among the unvaccinated subjects, and the average 

 mortality-rate for the treated was about one-fifth that for the un- 

 treated group. 



Another Army experience was that at Camp Taylor (U.S.A.) 

 reported in 1920 by Duckwall, 339 who employed as vaccine a saline 

 suspension containing in each cubic centimeter one thousand or- 

 ganisms of heat-killed pneumococci of Types I, II, and III. For 

 the 1,326 men receiving one, two, or three injections of vaccine at 

 intervals of seven to ten days the annual admission-rate per thou- 

 sand from pneumonia was 20.3, and for those receiving no prophy- 

 lactic treatment the rate was 54. The death-rate, similarly calcu- 

 lated, was 2.26 for the vaccinated and 8.76 for the unvaccinated 

 subjects. Considering the statistics for pneumonia together with 

 those for common respiratory infections, the author stated, "The 

 obvious conclusion is that the vaccine protects against pneumonia 

 and the common respiratory diseases in the proportion of five to 

 one." In comparison with the dosage employed by other observers, 

 that used by Duckwall is conspicuously small. 



In the same year, Borrell 143 described the effect of the adminis- 

 tration of saline suspensions of pneumococci (types not given) to 

 Senegalese troops stationed in France during the World War. 

 When two injections of a vaccine representing 3,000 and 6,000 

 million cocci were injected at seven-day intervals, the morbidity- 

 rate per thousand was thirty-six and seventy-three respectively 

 among the vaccinated in two battalions as against one hundred 



