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52
Diphtheria Immunisation at Schools.—The scheme of
diphtheria immunisation begun at Infants' Departments (and
described in the 1935 report) was continued during 1936. The
15 schools remaining from 1934 were visited, and out of 3,072
children in average attendance at the dates of the visits the parents
of 1,332 children, or 43.4 per cent., agreed to their children being
protected. The maximum percentage acceptance was 53.4, and the
minimum 26.7.
In addition, 3 other schools were visited, at which there were
a considerable number of children under 8 years of age.
A total of 1,612 children (1,410 of school age and 202 of preschool
age) were given a single dose of 0.5 c.c. alum precipitated
toxoid (A.P.T.) intramuscularly.
This procedure occupied a weekly session into mid-October,
when Schick testing was begun in order to test the efficiency of the
prophylactic given. By the end of the year testing had been carried
out at 12 schools. The experience of 1935 had suggested that one
dose of A.P.T. would be sufficient to protect 92.1 per cent., but as
testing continued during 1936 it became obvious that the immunity
obtained varied widely from school to school and was, on the whole,
disappointing. The results varied from 87.2 per cent. protected
at Winn's Avenue Infants to only 60.4 per cent. at Forest Road
Infants. Of 929 completed immunisations, only 73.5 per cent.
were successful after a single dose.
The response to artificially induced immunity will vary with
the efficiency not only of the particular prophylactic used, but also
with each batch, and also with the basic natural immunity of the
sample population—in this case the children at the particular
school.
The natural immunity will again depend on several factors,
notably the percentage of diphtheria carriers normally present at
each school.
It is obvious from the results obtained that the protection
afforded by a single dose of A.P.T. is not satisfactory and that
under no circumstances should the subsequent Schick test be omitted
with the single dose method.
The parents of all children found to be insufficiently protected
by one dose were invited to bring them to the Immunisation Clinic,
and all of the 143 who attended were fully protected after being
given a further half-dose (i.e., 0.25 c.c.).