Prjzyention of Pneumococcal Pneumonia by Immunization with Specific Capsular Polysacchardes

Many studies on prophylactic immunization against pneumococcal pneumonia have been made, using a number of dBerent antigenic preparations. Almost all investigators have concluded that immunization exerts a beneficial effect. In most of the studies, however, certain variables have clouded interpretation of the results. Among the variables, the following appear to be of greatest moment: differences in the composition of the immunized and control groups; uncertainty as to whether the specific pneumococcal types included in the immuniziig preparation were the same as those currently causing pneumonia; failure to determine whether the observed decline in cases in the immunized group 6s due to a decrease in cases caused by the pneumococcal types included in the vaccine; inadequate control of the antigenicity of the preparations used. The subject of antipneumococcal immunization has been reviewed recently by Heffron (1) and references will be made in the present paper to certain aspect3 only.