314 
Smallpox and Vaccination 
and 1851, of 3,094 cases 2,719 were under the age of thirty, or more than seven 
vaccinated persons under thirty were affected with smallpox for each individual 
above that age. In Dr Gayton's statistics relating to the period 1870 to 1883 
the corresponding proportion is to 1. In Dr Sweeting's referring to 1880 to 
1885 the proportion is 3 to 1, while in the epidemics of the last ten years two 
TABLE I. 
xige of Smallpox Attach in Case of Vaccination. 
Age 
Loudon, 1836-51 
Periods 
Cases 
Deaths 
0—5 
7 
2 
5—10 
56 
7 
10—15 
206 
10) 
15—20 
8G6 
49 \ 
20—25 
1058 
93 ( 
25—30 
526 
55 ( 
30—35 
210 
21 ) 
35—40 
102 
20 S 
40—50 
61 
10 
50—60 
2 
1 
60—70 
} 
70— 
\ 
0—30 
2719 
216 
30— 
375 
52 
London, 
Cases 
195 
786 
4504 
3761 
1297 
435 
134 
62 
9246 
1928 
1870-72 Loudon, 1880-85 Londou, 1892-95 London, 1902 
Deaths Cases Deaths Cases Deaths Cases Deaths 
38 
60 
238 
410 
257 
110 
30 
12 
756 
389 
26 
108 
256 
405 
632 
455 
1427 
455 
10 
59 
68 
79 
15 
16 
101 
98 
2 
188 
2 
265 
3 
533 
5 
654 
17 
639 
16 
1049 
45 
454 
16 
1017 
70 
370 
14 
827 
91 
234 
14 
616 
111 
293 
8 
726 
154 
89 
8 
254 
52 
24 
7 
105 
27 
10 
1 
36 
6 
1950 
39 
3099 
137 
1020 
52 
2564 
441 
26-4 
33-4 
28-6 
38-2 
Mean Am 22-6 24-5 
21-9 26-4 
persons under thirty years only are affected for each one over that age. In every 
town where there are statistics for a series of outbreaks of smallpox during the 
last thirty years exactly the same fact is observed. To mention Glasgow ; in 1872 
this proportion was 6 to 1, in 1892 to 1895 2^ to 1, and during the epidemic of 
1901 the ratio readied unity. Now there can be no doubt that a part of this is 
due to the gradual disappearance of adult persons ^jrotected by previous attacks 
of smallpox. In addition during the years immediately succeeding Jenner's 
discovery vaccination was performed promiscuously on young and old alike, and 
persons vaccinated in adult years must have constituted during the first sixty 
years of the century a very considerable proportion of the total vaccinated persons 
at higher ages, as it can easily be seen that any person in 1836 whose age was 
greater than thirty-seven must have been vaccinated at the earliest at an age 
corresponding to the difference of the actual age and of thirty-seven years. 
By 1870, however, both these influences must have to a considerable extent 
disappeared, and yet we see that the change referred to has been going on just 
as markedly since that date. Against these two factors must be set one which 
undoubtedly acts in the opposite direction, and that is the gradual better enforce- 
ment of vaccination during infancy, which, by continually providing a larger 
number of vaccinated persons at lower ages, ought if no other change were 
taking place to supply a greater number of cases at these ages. The influence 
of this should at least be sufficient, at any rate since 1870, to neutralise that due 
