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It will be seen that the case-rate at "all ages" was much greater among males than among
females, as was also the death-rate, especially in the case of the older ages. The case mortality
was, however, slightly lower among males than among females. In the age-groups adopted for
the purposes of this table, the greatest incidence of attack was upon males and females aged 20-25,.
and the greatest incidence of death was upon males and females under one year of age. The case
mortality was greatest among males under one year of age, and among females aged 1-2 years
of age.
The marked incidence of the disease on males of the later ages was equally conspicuous in
the outbreak 1893-4-5, and is no doubt due in large degree to the fact that the inmates of common
lodging-houses furnished a large number of cases in both epidemics. These houses are principally
occupied by males, the approximate numbers of male and female lodgers living in these houses
in London being 25,000 and 2,500 respectively. There is, however, a difference observable between
the two epidemics as regards the age distribution of cases of the disease, the relative incidence of
smallpox being smaller on the younger ages in 1901-2 than in 1893-4-5. This will be seen by
reference to the following table—

The percentages in the period 1893-5 are obtained from the tabular statements in the reports
of the Statistical Committee of the Metropolitan Asylums Board, which include all the cases
admitted into the hospitals, about three per cent. were not London residents.

In answer to the possible suggestion that the smaller relative incidence in the later period
on the younger ages of the vaccinated is explicable on the ground that fewer children were
vaccinated in recent years than before, it may be pointed out that there is absence of corresponding
increase of incidence on the younger ages of the unvaccinated, and this leads to the conclusion
that other explanation is required. Such explanation is probably to be found in the more complete
search made in the later period for cases of smallpox which would otherwise have remained
undiscovered and the various measures taken thereupon, tending to the more complete limitation
of the disease to the class in which it first attained marked prevalence.
Analysis of London cases of smallpox in respect of age and vaccination.
I am able, through the courtesy of the Metropolitan Asylums Board, to show in the following
table particulars of the condition as to vaccination of London inhabitants who were admitted
into the hospitals of the Board on account of attack by smallpox, and the case mortality of
each class at several ages. The deaths in this table, whether occurring in 1901 or 1902, are shown
in relation to the cases admitted during each of the two years. The table shows, as such tables
always do, the great difference between the fatality of the vaccinated and unvaccinated who are
attacked by smallpox; it shows the difference in the age incidence of attack by smallpox of these
two classes of the population, the unvaccinated having the greater proportion of their attacks in the
first ten years of life, the vaccinated having the greater proportion of their attacks after 20 years of
age; and it shows further the extent to which the fatality of the unvaccinated and those "without
evidence of vaccination" was reduced by vaccination after infection by smallpox.