View report page

120
persons over 10 years old and once vaccinated, the rate of smallpox
mortality actually observed, would give 100 deaths. For
100,000 over 10 years old and not vaccinated, the rate of small-pox
mortality actually observed, would give 5,100 deaths. Under the
general conditions and circumstances of the Sheffield epidemic
therefore, the twice vaccinated persons over 10 years of age as
compared with the unvaccinated persons of the same age living
in the town, had a 31-fold immunity against attack by smallpox,
and had a 640-fold security against death by small-pox.
Next is considered the position of vaccinated persons, aged over 10
years, who live in houses actually invaded by small-pox.
The attack rate of the vaccinated was 281
The attack rate of the unvaccinated was 686
The death-rate of the vaccinated was 14
The death-rate of the unvaccinated was 371
Thus the vaccinated people over 10 years of age had as compared with
the unvaccinated, a more than double immunity from attack by
small-pox, and a 26-fold security against death by small-pox.
The difference between vaccinated and unvaccinated when persons
over 10 are in question, is vastly less than in the case of
children.
C. Influence exerted by vaccination upon the people of all ages living
in Sheffield, under the common conditions of small-pox infection
in the Borough generally.
Per thousand of the number of persons of all ages in each
class:—
The attack rate in the vaccinated was 15.5
The attack rate in the unvaccinated was 97.0
The death-rate in the vaccinated was 0.7
The death-rate in the unvaccinated was 48.0
It follows that under the general circumstances of Sheffield during the
epidemic, the vaccinated persons of all ages had, as compared with
unvaccinated persons of all ages, a 6-fold immunity against attack
by small-pox. and that they had a 64-fold security against death
by small-pox.