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22 Report of the Medical Officer of Health for 1934.
The age grouping of the persons in whom immunity was
produced is given in Table XII.
Two of the 3,225 persons, who have become protected as
shown by a negative re-Schick test, obtained protection from
an attack of diphtheria which occurred shortly after they had
re-acted positive to the initial test. For this reason no immunising
injections were given, but the two children were tested again
after they had recovered from the attack, and the result of this
re-test was negative.
As it is important to be able to determine, as far as possible,
the time taken to produce immunity and the number of injections
required, a dissection of the protected cases is made in Table
XIII, giving this information. The two cases referred to in the
previous paragraph are not included in the table, which deals
with 3,223 persons. The table shows that, of this number, 2,890
became protected after the first series of injections and that the
majority of them received three injections, although 911 became
immune after one or two injections. Since the floccular preparation
has been used for immunisation, the proportion of cases requiring
only two injections has increased materially.
It will be noticed from Table XIII. that the time taken to
produce immunity is shewn to vary very much. The time which
elapses between the last injection of the immunising dose and
the re-Schick test depends to a large extent on the date when the
person concerned attends at the Clinic to be re-tested. Some
of it is, however, due to the actual delay in the production of
immunity. A number of the cases shewn in this Table which have
given final negative re-tests have had one or more positive results
before the final negative one was obtained.
2,122 of the persons who have been protected gave a negative
re-Schick test within six months after receiving the last dose
of immunising serum and a further 7 75 were negative within twelve
months. This means that 2,897 cases were known to have been
immunised within a year. There were good grounds for assuming
that a proportion of the remainder would have been found protected
if they had attended earlier to be re-tested.
In addition to the 3,225 persons who have been protected,
207 have completed the first series of injections but cannot be