Protective vaccinations 489 



Amongst the former only 36 died from plague, which corresponds 

 to 1*6 per cent. ; whilst amongst the unvaccinated persons the disease 

 carried off 1482 persons or 24'6 per cent. Vaccination, therefore, 

 according to these statistics, must have brought down the mortality 

 to one-fifteenth. The German Commission 1 , two members of which, 

 Koch and Gaffky, went to Damaun to be present at the vaccinations 

 and to observe their efficacy, pronounced in favour of Haffkine's 

 method. The English Commission 2 made reservations and criticised 

 the statistics of Haffkine and Lyons (who amongst others attribute 

 all the cases of deaths that occurred amongst the unvaccinated to [512] 

 plague), but in the end this Commission also recognised the utility 

 of the vaccinations at Damaun. 



The data collected with regard to the vaccinations at Undhera, 

 Hubli, and several other places in British India confirm the results 

 obtained at Damaun. The statistics collected at these localities 

 are certainly open to criticism, but the result as a whole is 

 none the less encouraging as regards this method of vaccination. 

 According to the conclusions of the English Commission the " inocu- 

 lations had a considerable effect in warding off plague attacks from 

 the inoculated.... The protection afforded by inoculation seems, how- 

 ever, never to be absolute 3 ." We do not, as yet, know the duration 

 of the immunity produced by Haffkine's vaccinations ; it cannot be 

 very long to judge from the experiments on animals, but it may last 

 for several weeks, probably even for months. 



The vaccinations by killed cultures may be especially useful when 

 it is a question of limiting the extension of an epidemic that is 

 already established. The ease with which the vaccine can be prepared 

 renders it possible to obtain very large quantities of it in a short 

 time, with which it is possible to immunise the entire population of 

 towns or districts. But, as the immunity by this method requires 

 several days for its development and as the injections of micro- 

 organisms, even when killed, may be very injurious during the 

 incubation period of plague or immediately before the infection, it is 

 necessary to limit the vaccinations to persons who are not in intimate 

 contact with the sick, or who are, from the beginning, exposed to 

 infection 4 . 



1 Arb. a. d. K. Gsndhtsamte, Berlin, 1899, Bd. xvi, S. 331. 



2 " Report of the Indian Plague Commission," London, 1901, VoL v, Chapter iv. 



3 Ibid. Chapter iv, p. 81. 



4 See Calmette, " Rapport sur les vaccinations centre la peste," Compt. rend. d. 

 X Congr. internal. d''kyg. de Paris, 1900. 



