622 ACTIVE IMMUNIZATION 



of contaminating microorganisms, but abscess formation is distinctly 

 rare. I, in common with others, prefer to find slight focal and con- 

 stitutional symptoms following the first one or two doses of vaccine. 

 In furunculosis, for instance, when the old lesions discharge a little more 

 and one or two others threaten to develop during a day or so following 

 the injection of vaccine, I feel assured that the ultimate result will be 

 good. In tuberculin therapy, however, the trend of opinion is very 

 much in favor of administering doses so small that no appreciable focal 

 or constitutional lesions will follow. Both the pathologic and the 

 immunologic process concerned in tuberculosis are somewhat different, 

 and in ordinary bacterin therapy a slight focal disturbance is desirable 

 and indicates that the vaccine in question possesses some potency. 

 Allen, who has an exceptionally rich experience in vaccine therapy, 

 frequently mentions the desirability of administering doses sufficiently 

 large to evoke slight reactions. 



Following the administration of a vaccine it is believed that the 

 quantity of opsonin in the body-fluids is temporarily decreased, and that 

 the inoculated person is, therefore, more susceptible to infection (nega- 

 tive phase) (Fig. 56). It can readily be understood how a vaccine 

 may temporarily depress the cells and defensive mechanism in general, 

 but just how it may bring about an actual decrease in opsonin it is 

 more difficult to understand, as the actual amount that may be used 

 in dealing with the vaccine itself must be small. Veterinarians are 

 careful not to expose cattle to infection immediately after they are im- 

 munized with anthrax vaccine, on account of this hypersusceptibility 

 to infection. In general, however, I have observed that most im- 

 munizators are prone to regard the question lightly, and to neglect 

 the importance of the negative phase, whereas some deny that it ever 

 exists. 



Contraindications to Active Immunization. It should be emphasized 

 that a properly prepared vaccine is a potent substance capable, when 

 given in excessive dosage or when otherwise injudiciously administered, 

 of doing much harm. A vaccine stimulates body-cells, and unless the 

 cell can withstand the stimulation, the administration of vaccine may 

 do actual harm. This is the main reason why vaccines should be used 

 very cautiously, if at all, in the treatment of severe generalized infections. 

 In passive immunization the conditions are different, as the body-cells 

 are not taxed, but rather, through the neutralization of the toxic sub- 

 stances which they are combating, they are relieved, and an antibody- 

 laden serum may, therefore, be freely administered in severe infections. 



