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Means Adopted to Prevent Spread of Epidemic.
These consisted of vaccination, isolation, disinfection, the compulsory notification of chicken-pox,
and appointment of experts in small-pox by the London County Council, issuing of posters
and handbills, examination of contacts, house to house inspection, closure of schools, and
quarantine.
Vaccination.
The subject of immunity in general against infectious disease has been one of the most difficult
problems in medicine since the latter became a science. It has been known from very ancient
times that, when a person recovered from an attack of most of the infectious diseases, he was
rendered immune, with very few exceptions, to a second attack of the same disease. When I say
with few exceptions, I mean that the rule is not absolute, because some people have been known to
have second, and even third attacks of measles, scarlet fever, small-pox, etc.; but still this does
not invalidate the general principle. It was found in pre-vaccination times that if a person was
artificially inoculated with small-pox virus he contracted, as a general rule, a mild form of the
disease, which rendered him immune against the severer form. There is considerable risk, however,
in this method of producing immunity, but so great were the ravages of small-pox in the eighteenth
century that numbers of people were found willing to take this risk when inoculation was
introduced by Lady Mary Montague. Jenner, in the end of the eighteenth century discovered
that a similar result could be produced by inoculation with cow-pox, and this has been followed
by a steady and continuous decline both of the attack and death-rates in small-pox, which has
been just in proportion to the efficiency with which vaccination has been carried out in the
community.
It is only within the last year or two that cow-pox has been proved to be small-pox, modified in
such a way by passage through the cow that it renders the subject of inoculation immune from
small-pox without producing the latter disease in its contagious form.
The amount of immunity produced by vaccination varies according to the efficiency of the
vaccination, i.e., the number of marks up to a certain point, and four or five marks have been
found to produce a sufficiently lasting immunity. One mark may produce a certain amount of
immunity, but it only lasts a very short time. A common view, and one which is mistakenly or
wilfully propagated by anti-vaccinators is, that vaccination is claimed by vaccinators to render
one absolutely immune for all time. This is very erroneous, for the immunity produced by
vaccination as well as by natural acquisition of small-pox or any other infectious disease, tends
to fade and become less as time goes on. Therefore, to keep one absolutely immune to small-pox,
the subject would require to be vaccinated at intervals. These intervals differ within very wide
limits for different individuals. A good primary vaccination renders a few people immune for
the rest of their lives, so that they cannot be got "to take" a second time, and immunity in a few
others may only last a year or two. Between these limits there is every gradation.
The theory is, that when a person recovers from an attack of a certain disease, the cells
of the body manufacture an antitoxin which neutralises the virus of the same disease, and leads
to recovery from the particular attack, or immunity from this disease if re-introduced at a later
period into the system. A great many people are naturally immune to some infectious diseases,
small-pox among the number, otherwise this disease would have depopulated the globe long ago.
Now, looking at Tables II. and III., it will be seen that the death-rate on the whole is
favourable to the vaccinated, and as only about "four" patients out of the whole number have been
re-vaccinated, it shows that the primary vaccination has left some trace of immunity. The
same remark applies if one looks at the age periods, the only apparent exceptions being that
between 5 and 10 and 20 to 25 of Table II. This only shows that some persons are naturally
immune; but that it would be most unsafe to draw conclusions unfavourable to vaccination
from these age periods alone, will be shown by looking at the same age periods in Table III.,
which deals with larger numbers, and is therefore a safer guide.
On the occurrence of a case of small-pox, the vaccination officer was at once communicated
with, and he made arrangements with the public vaccinators to at once visit the infected house
and endeavour to get all the healthy inmates vaccinated or re-vaccinated, as the case might be.
In the majority of cases he was successful, and if they were done within 24 or 48 hours of
becoming infected, they did not develop small-pox. Such quick vaccination did not always take
place, because the cases were often late in the disease, say three to five days after the rash made
its first appearance, before they were reported, or because the people took a day or two before
they could make up their minds to be done. As a consequence, it was not an uncommon thing
to find the vaccination and a very mild attack of small-pox developing simultaneously. This
was not at all satisfactory from a public health point of view, because one had great difficulty
convincing the patient that he had small-pox, and that it was not a vaccination rash from
which he was suffering. He frequently, therefore, walked about with a mild attack of small-pox.
There seems to be a popular impression that the milder the attack of small-pox, the less
dangerous it is to others. There is nothing more erroneous, and it cannot be impressed on
people too strongly, that though they have a mild, and as far as they are concerned, trivial,
attack of small-pox, they may give it in a severe and fatal form to some person who is more
susceptible than they are.
As mentioned before, only four out of the 297 who were attacked with small-pox had been
re-vaccinated, and among these the most recent re-vaccination was eighteen years before, the
longest being 40 years previously. This shows the advantage of re-vaccination. Among the
officials of the Public Health Department, including the clerks (for some patients with small-pox
walked down to the Town Hall, Lower Road) none contracted small-pox who had been re-vaccinated,
the only ones who took the disease being two disinfectors, neither of which had been vaccinated