498 BIOLOGY OF PNEUMOCOCCUS 



Field are not highly conclusive, but it was his impression that a 

 positive effect in lowering the incidence of pneumonia was obtained 

 by means of the vaccine. 



Of more significance is the report of the study made by Mc- 

 Coy, Hasseltine, Wadsworth, and Kirkbride. 875 To 17,752 inmates 

 of various state institutions was given a single subcutaneous injec- 

 tion of one cubic centimeter of lipovaccine containing approxi- 

 mately ten billion pneumococci of the first three types, while 

 18,595 subjects and 7,992 newly admitted patients were reserved, 

 untreated, as controls. Observations extended over a period of two 

 years, and in the final analysis of the data it appeared that of the 

 cases of pneumonia occurring among the vaccinated subjects 18.0 

 per cent were caused by organisms of Types I, II, and III, while in 

 the control series the percentage was 23.6 — scarcely a satisfac- 

 tory degree of protection. From theoretical considerations the 

 comparative failure of lipovaccines may be ascribed to lower anti- 

 genic potency of bacteria when suspended in oil — an opinion 

 shared by many immunologists and expressed by Cecil in 1923.* 



In a paper by Malone 864 and in one by King 714 appearing in 

 1925, the view was expressed, based on the results of the vaccina- 

 tion of 2,500 troops in India, that vaccination as practiced was 

 probably without any protective value. The vaccine contained only 

 pneumococci of Types I and II in such a concentration that the 

 dose, given twice subcutaneously at an interval of a week, con- 

 tained 5,000 million cocci. A case-rate among the vaccinated of 9.3 

 when compared to the only very slightly higher rate of 10.7 for 

 the unvaccinated controls would justify the authors' unfavorable 

 opinion. However, a less pessimistic view concerning the value of 

 vaccines in the prevention of pneumococcal infections was ex- 

 pressed by Cole in 1920, 262 who also in 1934r 66 concluded: "It is 

 not impossible that, even with our present knowledge, something 

 could be accomplished by vaccination." Cole, in discussing the 



* A review of the prophylactic vaccine treatment of pneumonia was pub- 

 lished by Cecil-o3 j n Medicine in 1925. 



