208 MODERN BIOLOGIC THERAPEUSIS 



prophylactic inoculation persists. Although the 

 prophylactic vaccine has now been in use in the 

 American service for over four years, there is 

 as yet no indication of loss of immunity. The 

 present practice in the United States Army is 

 to revaccinate against both smallpox and ty- 

 phoid fever at the commencement of each en- 

 listment period, which is once in four years. 



Revaccination Bevaccination should be per- 

 formed more frequently in children than in 

 adults. It is a good plan in vaccinating against 

 typhoid fever to use the method used in small- 

 pox; namely, to vaccinate once in infancy, once 

 in childhood, once in youth, and once in adult 

 life. This would probably give good protec- 

 tion. 



Practical Application Typhoid vaccination 

 is carried out in almost all the larger hospitals 

 of New York City; the nurses, the house staffs 

 and the administration staffs being immunized. 

 All male and female nurses and attendants of 

 the Paris hospitals are compelled to be vacci- 

 nated against typhoid fever. The extension of 

 this measure to certain phases of civil life is 

 definitely indicated in the presence of an epi- 

 demic; or for those leaving their homes for 



