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giving a mortality per centage of 41.66. The larger number of
cases of small-pox in vaccinated persons is, of course, due to the
fact that by far the larger proportion of the population at that
age-period have, at some time or other in their lives, been
vaccinated.
There are many things to be learned from a study of this Table
by itself, and also in conjunction with the Table on sex and age
incidence. There are three broad facts which stand out with
clearness:—
(1) That small-pox among the vaccinated is now-a-days mainly
a disease of adults, because children are protected by primary
vaccination and adults are not protected by re-vaccination. (92
per cent, of the vaccinated cases were over 15 years of age).
(2) That among the unvaccinated, small-pox is still, in great
measure, a disease of the young as it was in prevaccination daye.
(73 per cent, of the unvaccinated cases were under 15 years of
age).
(3) That the mortality rate among the vaccinated is at all ages
much less than among the unvaccinated, and that this difference
is very striking and complete in children because of their recent
vaccination.
Those who advocate vaccination and re-vaccination as protective
in a greater or lesser degree against small-pox do so upon three
main grounds. In the first place, they claim that, other things
being equal, persons who have been vaccinated (especially within
ten years) are less liable to attack from small-pox. This is
abundantly established by the figures quoted above. In the second
place, they claim that persons who have been vaccinated, and yet
on account of their greater number in the population, and, therefore,
their consequent greater probability of infection, are attacked
by small-pox, do not die so readily from the disease as those who
have not been vaccinated. This claim also is more than proved
in the returns quoted above. In the third place, they claim that
the protection afforded by vaccination depends upon the efficiency