LIVE POLIO IRUS VACCINES

578
Efficacy-Field Evidence
some of them. How is coli-enteritis to be prevented?
Scarcely by destroying coli-bacteria, a
very unrealistic task. A more realistic approach
would be to seek means of correcting the pathological
reaction of the child organism.
Turning back to poliomyelitis, or better, to
the problem of eradicating poliomyelitis, one
must clearly ask: In what way can and should
we solve this task-by destroying the agent or
by correcting the pathological reactions of the
organism?
Poliomyelitis infection may be compared with
an iceberg: most of it is under water and only
the top, above. The part below the water is
like asymptomatic infection and the top, a
paralytic disease. What should be done to prevent
collision with the iceberg-sinking or destroying
it?
It seems to me that Salk vaccine acted only
by correcting the pathological reaction of the
human organism, whereas live vaccine makes
practically possible the destruction of the poliovirus,
that is, complete destruction of the iceberg.
The live polio vaccine puts forward the
problem-principally and practically-of eradication
of poliomyelitis up to the complete
destruction of the agent as a biological species.
However, this task is not so simple as it may
seem, and therefore in beginning the offensive
against poliomyelitis one must draw up a good
strategy and a flexible tactic.
There are in human organisms two large
cavities which communicate with the external
world: the respiratory and the intestinal tracts.
Numerous inhabitants populate them. Some
appear in the host's early infancy and leave
when the child's organism ripens immunologically
and becomes an inconvenient place of
habitation. Others come periodically for short
visits. And some come to stay as long as the
host lives. This parasite population varies from
host to host, and not always is there a place for
a newcomer like a vaccine strain of poliovirus.
Therefore, there are many specific problems
connected with the necessity of increasing the
efficacy of vaccination with the live poliomyelitis
vaccine.
Mass vaccination is only the first step toward
solving the problem of an offensive against poliomyelitis.
Thereafter must follow a careful study
of the conditions necessary for the successful
immunization of different groups of the population-in
cities and villages, in families and
kindergartens, among different socio-economic
groups, in different climatic zones, and at different
seasons. It is necessary to determine the
best and surest ways. to suppress virus interference,
remembering that it takes place not on
a neutral soil but within the human organism,
which helps itself with its immunological reactions.
Finally, one must elaborate different schedules
of immunization under different conditions and
in different countries.
And yet, in spite of all the difficulties which
we already know and those which will confront
us, the problem of eradication of poliomyelitis
will be solved in the next years.
I should like to conclude by mentioning again
the newly developing theoretical epidemiology,
based on research done in the field of poliomyelitis.
Papers given here show how far we
have come from Topley's mouse towns.
I think that the further development of ecological
epidemiology or pattern epidemiology
will help us not only win the fight against poliomyelitis,
but also intervene actively in the life
of the inhabitants of the large cavities of the
human organism-to destroy weeds and to seed
cultured plants.
(The complete text of the paper is as follows:)
THE PROBLEM OF MASS VACCINATION
AGAINST POLIOMYELITIS
The usual steps taken to combat epidemicsearly
detection and isolation of the sources of
infection, quarantine, and disinfection of the
foci of the disease-are palliative measures in
the case of poliomyelitis because of the widespread
occurrence of symptomless virus carríage
and the impossibility of diagnosing all the inapparent
infectious forms of the disease.
It is therefore generally accepted that successful
control of the epidemic spread of poliomyelitis
can be achieved only by really large-scale
immunization of the whole susceptible population
and, in the first instance, of the age groups
from 0 to 15-20 years of age.
In view of this, the task of vaccinating many
millions of persons against poliomyelitis, which
is a comparatively rare disease, makes it necessary
that the vaccine should fulfill certain par-