LIVE POLIO IRUS VACCINES

The occurrence of poliomyelitis in certain
areas where extensive use of vaccine had been
made in previous years has yielded evidence of
lower attack rates in the immunized than in the
non-immunized segments of the population. But
the occurrence of some cases among those receiving
vaccine has indicated the need for additional
feedings of oral vaccine if an adequate
immunity of the population is to be ensured.
The concept of eradication of poliomyelitis
The widespread use of potent inactivated vaccine
may well lead to a substantial reduction in
the numbers of cases of paralytic poliomyelitis,
but it can do little to eliminate the causal virus
from the gastrointestinal tract of man. The
possibility of eliminating poliovirus as a human
pathogen has been brought much nearer by the
development and practical application of live
poliovirus vaccines. We can indeed look forward
to the eventual eradication of poliomyelitis, as
we can look forward to the eradication of diphtheria,
smallpox, and other preventable infectious
diseases by means of specific prophylactics.
The members of the Conference fully realize
that the attempted elimination of such a wellestablished
and almost universally prevalent
Summary of the Conference 603
Summary of the Conference 603
pathogen as poliovirus is a gigantic task, at
present impractical in many countries. The
Conference therefore notes with the greatest of
interest the campaign aimed at the almost complete
eradication of poliomyelitis now being
conducted in the USSR.
The first step in such a campaign is the mass
vaccination, by feeding attenuated viruses within
a short period of time, of the whole population,
or at least those age groups most susceptible to
infection. Following this "blanketing" with
viruses, special studies will have to be conducted
to determine the most feasible means of maintaining
the resistance of the population. These
studies would have to take account of differences
in the ecological behavior of polioviruses under
various climatic conditions, in various socioeconomic
groups, and in communities with differing
opportunities for dissemination of virus,
such as institutions, rural areas, small towns,
and large cities.
This concept of complete eradication of poliomyelitis
is indeed bold, and it would be well to
prepare for disappointments and for the unexpected.
The whole problem of the eradication
of poliomyelitis is worthy of the closest study
not only in the field, but at the theoretical level.