VACCINE THERAPY IN THEORY AND 



PRACTICE 



By D. W. C ARM ALT JONES, M.A., M.B. Oxon. 



It has long been observed, that after recovery from an acute 

 bacterial disease, a person is not liable to contract it again for 

 a longer or shorter period. Such a person is said to be 

 " immune " and to possess " active immunity." It is possible to 

 produce immunity by artificial means, and two distinct methods 

 are employed for this purpose, between which confusion some- 

 times arises. By one method an animal is infected with the 

 disease in a modified form, and after its recovery its "immune 

 serum " is drawn off and injected into patients with a view 

 to conferring immunity upon them : such immunity is called 

 " passive," and this is the object of sero-therapy. The other 

 method consists in injecting into the patient the actual organisms, 

 killed by heat, which cause the disease, and thereby conferring 

 active immunity. 



The latter method is known as " Vaccine therapy," and a 

 vaccine, as used to-day, is a suspension of micro-organisms in 

 sterile normal saline solution, containing a little antiseptic. 

 The organisms have been killed by heat, their sterility is tested, 

 and their number per unit of volume is correctly estimated. 



It is this method of conferring active immunity which it is 

 proposed to discuss in this article. Vaccine therapy has a far 

 wider application than has serum therapy ; it is easier of access 

 and capable of accurate standardisation, and there can be little 

 doubt that it will be the method of immunisation of the future. 

 Serum therapy will not be further referred to here ; it has 

 indeed been previously dealt with in this journal by Dr. 

 Inman. 1 



In the past, artificial immunity has been induced chiefly for 

 prophylactic purposes, in order that persons likely to be 

 exposed to infection might be protected, but of recent years it 

 has been introduced in the course of a disease as a method 

 of cure. 



1 Inman, Science Progress, Oct. 1906. 

 597 



