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circumstances. The experience of the year has, I think, justified this recommendation.
... As antitoxin has proved itself the best method of treatment, so
immunisation appears to be our best prophylactic."
The above-mentioned authoritative views form, to a large extent, the justification
upon which such action as has been taken by public health authorities in this country
has been based.
As regards actual experience of active immunisation in this country, where
it has been adopted in a particular area, the number of children immunised in proportion
to the number of susceptible children is so small, and the period during
which this preventive measure has been employed, so short, that any marked variation
in the incidence of diphtheria can hardly be expected. On the other hand, there
is strong evidence that where the population of institutions, such as the staffs of
fever hospitals, residential schools and the like, have been immunised, a marked
diminution in the incidence of diphtheria has followed.
There is, as yet, however, insufficient evidence to demonstrate the effect, as
regards the incidence of diphtheria, upon any given community, even if the whole or
the great majority of the child population were actively immunised, because, so far
as can be ascertained, there is no place in the world where active immunisation
has been carried out with such completeness as to render it possible to draw any
justifiable and certain conclusion.
In New York and other large American towns immunisation has been carried
out on a wider scale than elsewhere. In New York City over 600,000 children
were tested, and over 400,000 children were immunised between 1916 and 1926.
The child population of New York City, i.e., those of school age and under, is about
1,650,000. Coincident with these immunisations there occurred a decline in diphtheria
mortality, for whereas the average number of diphtheria deaths for ten years previous
to 1919 was 1,337, the corresponding figures for 1924,1925 and 1926 were respectively
715, 663 and 477. A corresponding decline was observed in other American cities.
The conclusion must not, however, be drawn that the decline was entirely due
to the immunisations which had been carried out, although they may have exerted
some influence, because (a) after the period of cyclic prevalence which had been
experienced in preceding years, the incidence of the disease would normally be
expected to fall, and (b) the proportion of children immunised could not be expected
to make any very marked difference in the epidemicity of the disease.
That there is real need for caution in ascribing the remarkable diminution in
the prevalence of the disease in New York between 1924 and 1926, to active immunisation
alone, becomes clear from the fact that during the first six months
of 1927, there has been a notable rise both in the incidence and mortality from
diphtheria in New York City, no fewer than 8,596 cases, with 435 deaths, having
occurred up to the end of June, 1927.*
It is stated that the evidence, so far provided by results in America, points
to an effective protection for at least six, and possibly ten, years. According to
authoritative American observers, as a result of observation over periods ranging
from 3 to 6 years, no child who received the full immunising course, and had given
a Schick negative reaction, subsequently contracted diphtheria.
Having regard to all the evidence so far available, which is set out in extenso
in the report published by the Medical Research Council, and to the pronouncements
of the Ministry of Health, there can be no reasonable doubt that active immunisation
is now regarded by many prominent members of the medical profession as a valuable
preventive measure.
*The total number of cases reported as occurring in New York City during the whole
of 1927 was 14,778 as compared with 7,367 in 1926; 9,051 in 1925; and 9,687 in 1924;
whilst 716 cases (approx.) proved fatal in 1927 (figures for preceding years are shown in
context above).