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re-vaccination existed. In the absence of any precise knowledge as to the proportion of the London
population who have been re-vaccinated, it is impossible to compare the incidence of the disease on
this class of the population with that on those who have only been vaccinated in infancy. But even
if it be assumed that the whole of the 276 persons mentioned had been successfully re-vaccinated,
which no doubt was not the case, this number must stand in very small proportion to the total
number of re-vaccinated persons in the London population, 351,481 of whom were re-vaccinated
at the expense of the rates during the one year ended September, 1902.
There cannot be doubt that the administrative measures adopted during the years 1901-2
were largely instrumental in limiting the prevalence of smallpox. This is shown by the smaller
relative incidence of the disease upon the population at younger ages in 1901-2 as compared with
1893-4-5, a circumstance which is especially noteworthy in view of the increase in the number
of children unprotected by vaccination. When, moreover, it is recollected that the administration
for the one community of London was vested in 29 separate sanitary authorities, and in 31 vaccination
authorities, and the attitude of all these authorities to the subject of vaccination was by
no means the same, it is matter for congratulation that the four and a-half millions of the population
escaped with not more than some 10,000 cases of, and not more than 1,600 deaths from,
smallpox.
As yet it is impossible to give particulars of the vaccinations performed during this period,
and it will never be possible to state the total number of the London population who were revaccinated,
but inasmuch as during the year ending September, 1902, as many as 351,481 persons
were re-vaccinated at the cost of the rates, and that large numbers of other re-vaccinations took
place, the cost of which did not fall on the rates, the susceptibility of the population to smallpox
must have been materially altered as the result. The matter for regret is that with all the willingness
which the London population shows to resort to vaccination for protection against smallpox,
no system exists which provides for re-vaccination, as a matter of routine, at an age when the
protection afforded by the primary vaccination of infancy is waning, and before there is exposure
to smallpox infection. That such a system would largely reduce the mortality from smallpox,
there is no question, and indeed, it is the more necessary since the State has provided for the
exemption from the requirement of the vaccination law of the children of the "conscientious
objector." The interests of these children especially require that they should not be exposed to
the infection of cases of smallpox. Many of these cases now occur among persons who, while they
are not themselves objectors to vaccination, in the absence of any statutory incentive do not
renew the state of insusceptibility to smallpox which is for a time conferred upon them by their
vaccination in infancy.
Chicken-pox.
On the 28th January, 1902, the Council made an order that section 55 of the Public Health
(London) Act, 1891, relating to the notification of infectious disease should apply to the disease
known as chicken-pox. The effect of this Order was to make compulsory the notification of
chicken-pox in the county of London for a period of three months dating from the 7th February,
1902. This period was subsequently extended, and the Order remained in force until January 6th,
1903. The course adopted by the Council was recommended in a report of the Public Health
Committee dated 21st January, 1902, in which it was pointed out that in the course of the smallpox
outbreak in London, which began in the middle of the year 1901, the failure to distinguish
between chicken-pox and smallpox had led to the spread of the latter disease.
The compulsory notification of cases of chicken-pox occurring among the population of
London for a period of nearly twelve months provides sufficient statistical material for discussing
some points of interest in the behaviour of this disease. It is common knowledge that chickenpox
is rarely fatal. Only a few deaths from this disease are recorded each year in the returns
of the Registrar-general, and probably some of these may be deaths from unrecognised smallpox.
The mortality records, therefore, even over a long series of years, supply no answer to questions
concerning seasonal variations in the prevalence of the disease, age and sex incidence, differences
in the distribution of the disease in regard to locality, etc.
During the time that the Order of the Council was operative, 25,009 cases of chicken-pox
were notified in London, this number giving a case-rate of 5.9 per 1,000 living per annum. This
rate is considerably greater than the mean case-rate obtaining for the other notifiable diseases.
Thus the mean case-rates obtaining in the decennium 1891-1900 were—for scarlet fever, 4.8;
diphtheria, 2.65; enteric fever, 0.8; and erysipelas 1.4 per 1,000 living. The following table
shows the number of cases notified in each week of the period during which the disease was notifiable,
and the accompanying diagram (VII.) shows the weekly notifications in relation to the mean
of the whole period. For the purpose of comparison the curve formed by the weekly number of
notified cases of smallpox is also shown. So far as the figures for such a limited period as 48 weeks
can be trusted to indicate the relation between chicken-pox prevalence and season, the diagram
suggests a close similarity between chicken-pox and measles in this connection. It will be seen
that the curve exhibits two distinct maxima, one in June and the other at the end of November
and beginning of December. The measles curve, based on the mortality in London during the
60 years 1841-1900, which was published in the annual report for the year 1900, also exhibits two
maxima—one in June and the other in December. It is, no doubt, unsafe to draw precise conclusions
as to the character of the seasonal curve of chicken-pox on the figures furnished by the limited
period during which notification was compulsory in London, but the close resemblance between the
chicken-pox and measles curves is noteworthy although the possibility of coincidence must not be
overlooked.