PROPHYLACTIC IMMUNIZATION OR VACCINATION 679 



been stamped on the skin by a sharply cut die are quite characteristic. 

 Poor scars are those that were said to have been the result of vaccination, 

 but in very many instances they are so indistinct as to make it difficult 

 or impossible to recognize them as vaccination-marks. 



Revaccination. One successful vaccination does not necessarily 

 confer an absolute immunity against smallpox, and failure to recognize 

 certain limitations in this respect has done harm by enabling anti- 

 vaccinationists to create a distrust in the minds of the ignorant by 

 pointing to individual instances of failure. That a person who has 

 once been vaccinated may afterward suffer from smallpox is undoubted, 

 but usually the vaccination was performed many years previously, 

 and in any case the disease, when it does occur, is relatively mild (vario- 

 loid). 



There can be no doubt but that the immunity gradually diminishes. 

 Perhaps seven years may be taken as the average period of fairly com- 

 plete protection. Children should be vaccinated within the first year 

 after birth, revaccinated upon entering school, and again after leaving it. 

 If smallpox is prevalent, all persons should be vaccinated, regardless 

 of the fact that they have previously been vaccinated. Only those who 

 have had smallpox may be excused. If, as a matter of fact, persons are 

 still immune, the vaccination will not "take" and no harm is done, 

 whereas if it succeeds, such persons will have the satisfaction of knowing 

 that their immunity has been increased. Hence it cannot be too 

 strongly emphasized that not only vaccination, but revaccination, is 

 indicated to protect the individual and society against smallpox. Dwyer 

 claims that a person should be revaccinated repeatedly in succession 

 until he fails to react; even a slight "take" would indicate incomplete 

 immunity. 



Occasionally a non-immunized person refuses to "take," but vac- 

 cination should be repeated three or four times, as failure is not infre- 

 quently due to old and inactive virus, and the actual number of persons 

 absolutely insusceptible is very small indeed. 



Risks of Vaccination. When vaccination is properly performed with 

 a good virus, the risk of permanent injury to life or limb is almost 

 negligible. 



1 . Tetanus. The most serious of the inj uries that have been attributed 

 to vaccination is tetanus. The tetanus bacillus and its spores are so 

 wide-spread in nature that opportunity presents itself for contamination 

 of the vaccinal wound and the virus itself. Every precaution should, 

 therefore, be taken in the preparation of virus, and it is especially im- 

 portant that physicians and laymen should realize the necessity for 



