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A determined attempt is being made to follow up the immunised cases from two to three
years after the completion of the original immunising course. As far as circumstances permit, such
persons are sent for in rotation, and re-Schick-tested, with a view to finding out how many cases
show a tendency to revert to the susceptible state. With only one clinic a week it has been impassible
to deal with as many of these subjects as would have been desirable, but it is hoped to make more
ample provision for this type of work in 1934.
The number of subjects actually tested after from 2 to 3 years from the date of original immunisation
was 153, this number actually including 58 persons who had been originally naturally
immune.
The results were :—
Natural Immunes. (58 subjects).
Still Schick-negative, 57.
Schick-positive, 1.
Immunised Subjects. (95 children).
Still Schick-negative, 83.
Again Schick-positive, 12.
It will thus be seen that among the naturally immune group the percentage of reversion to
susceptibility amounted only to 1.7%.
In the immunised group the percentage of reversion appeared to be 12.6. In this connection,
it must however be borne in mind that the reversion to some degree of apparent susceptibility does
not necessarily mean that such subjects would be likely to contract Diphtheria. The essential factor
in immunisation appears to be the training of the body to produce antitoxin when required. The
original production of the Schick-negative state in an initially susceptible person provides some
guarantee that the body has received a good training in antitoxin production. Even though a subject
may subsequently show a positive reaction, the first trace of diphtheria infection is often enough
to restore the activity of the antitoxin production mechanism, so that the person again becomes
protected very rapidly by these means, and Diphtheria does not develop.
Of the 12 originally immunised persons who had reverted to some degree of Schick-positive
reaction, 5 received further immunising injections, and were subsequently shown to have been rendered
Schick-negative again.
A further 6 received extra injections but have not yet been re-tested.
One case had no further injection.
Up to the date of this report no child immunised at the clinics has contracted diphtheria.
There have been eight cases in which there was a suspicion of Diphtheria in subjects believed to be
immune. Full investigations showed that the diagnosis was faulty in 6 cases, which were subsequently
shown to be suffering from other conditions.
The two remaining cases were found to be carriers of Diphtheria bacilli only, and they presented
no clinical symptoms of the disease, and took no harm from the presence of the organism.
On the 22nd December a child who had removed to Romford was notified as suffering from
a very mild attack of Diphtheria. This child had not been immunised at the clinic, as it appeared
to be naturally immune.
In this connection it must be plainly stated that in course of time we shall undoubtedly meet
with a few mild cases of Diphtheria, both among immunised and naturally immune subjects. Such
cases are due to no fault in the methods adopted. They occur as a result of the ever changing factor
of the human body. Some persons are easy to immunise and retain the protection almost indefinitely.
Conversely others are initially difficult to immunise, and tend to lose the protection rapidly.
Only by careful and thorough work can we hope to maintain the number of apparent failures
at a minimum. This we are attempting to do, as previously mentioned, by following up the old
cases, and by dealing with the new ones with the utmost thoroughness. It is indeed satisfactory
that during the whole time this work has been in progress at Heston and Isleworth that one is only
obliged to record one apparent case of Diphtheria in a child considered naturally immune, no cases
among our immunised subjects, and of course, no deaths in either class.
A very careful and exhaustive analysis of all the figures obtained up to the end of 1932 was
given in the annual report for that year.
The figures which we have to add are not sufficient materially to affect those statistics, which
are based on a considerable number of cases.
It is proposed to re-analyse all our figures when the number of additional cases appears to make
this worth while.
The figures for 1933 added to those for previous years show that a total of 3,641 certificates
have been issued up to the end of 1933.
Of these 700 were given to naturally immune persons.
2,941 were given to immunised subjects.
The methods previously utilised at the clinics have again been found satisfactory, and the
larger third dose of 1.5 c.c. of T.A.M. has been found to be of definite advantage. By the date of
the next report, sufficient figures will be available which should leave no doubt as to the value and
desirability of this procedure.
G. BOUSFIELD, M.D. (Lond.).
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