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Intercurrent.—One case developed a moderately severe attack
of diphtheria one week after the 2nd injection of T.A.M. It gave
negative reaction on re-test.
Two other cases developed mild diphtheria, both starting one
week after the 3rd injection of T.A.M. Both were Schick
negative on re-test later.
Acquired immunity to diphtheria does not attain a level
sufficiently high to give protection against the disease, until three
or four months have elapsed after the last injection. A child
cannot, therefore, be regarded as immune during this period.
Subsequent.—Only 3 cases have come to notice of diphtheria
in children who have undergone an immunizing course at the
Clinic. All were treated in the Borough Hospital. One was a
mild case of Faucial Diphtheria and another a mild case of Nasal
Diphtheria. Neither had any marked clinical symptoms, but
swabs taken were positive. The third case was a moderately
severe case with membrane on both tonsils, some general
toxaemia and foetor. She was given 40,000 units A.D.S. on
admission, and this was repeated the following day.
The parents of children who have had their children immunized
against diphtheria, at perhaps some inconvenience to themselves,
are not unnaturally somewhat annoyed if their children
subsequently develop diphtheria. The susceptibility of a person
to diphtheria depends in the main on two factors, (1) the individual
degree or level of immunity to the disease, (2) the type of
diphtheria organism whether of low or high virulence.
If a person's level of immunity is very low an organism of
low virulence may cause clinical symptoms. A person with an
intermediate level of immunity might be protected against a
bacillus of low virulence, but might succumb to one of high
virulence, the return of the disease probably being mild or
moderately severe. A high level of immunity should give protection
against germs of high virulence.
Immunization with the prophylactics at present in use does
give a high level of immunity. It is known, however, that this
level may not be maintained indefinitely, hence the importance
of having a repeat Schick Test carried out two or three years
after concluding the course. If, then, a child who has been
immunized, but whose level of immunity has been reduced to the