484 Correlation between Vaccination and Smallpox 
TABLE II. 
All Cases except those in which Vaccination was Doubtful, 1901 — 2. 
Vaccination and Severity. 
Recoveries 
Deaths 
Totals 
Un vaccinated . . . 
1525 
753 
2278 
Vaccinated 
6240 
705 
6945 
Totals 
7765 
1458 
9223 
r= - •4741. 
TABLE III. All Cases, 1901 — 2. Vaccination and Severity. 
Eecoveries 
Deaths 
Totals 
Unvaccinated or doubtful ... 
1790 
924 
2714 
Vaccinated 
6240 
705 
6945 
Totals 
8030 
1629 
9659 
,•=-■4922. 
Of these three values I prefer that of Table I., as I believe that a majority of 
the doubtful class were really vaccinated. This class includes not only those cases 
stated to have been vaccinated, in whom the scar was certainly absent, but also 
those in which the presence or absence of the scar could not be affirmed with 
certainty on account of the abundance of the smallpox eruption. This latter class 
is much more numerous than the former and naturally has a high death-rate. 
Consequently the position assigned to the doubtful class in the table has an 
influence on the value of r out of proportion to the size of the class. 
The reasons for believing the majority of the doubtful cases to have been 
vaccinated are : 
(a) In those cases where direct observation fails, it seems reasonable to attach 
value to the statement that the patient had been vaccinated, as likely to be right 
in the majority of instances. 
(b) Smallpox affects vaccinated and unvaccinated persons at very different 
ages ; not only is the prevailing age different in the two groups, but also the two 
groups only overlap to a moderate extent. The age distribution among the 
doubtful cases coincides most closely with that of the vaccinated class, as is seen 
in the adjoining table. 
TABLE IV. 
Age incidence among the Vaccinated, Unvaccinated and Doubtfully Vaccinated. 
Age 
0-9 
10-19 
20-29 
30-39 
JfO-^9 
50-59 
Over 60 
Totals 
Vaccinated 
134 
1163 
2517 
1755 
893 
320 
163 
6945 
Doubtful cases ... 
33 
73 
98 
77 
62 
52 
41 
436 
Unvaccinated ... 
1274 
619 
244 
90 
31 
13 
7 
2278 
