LIVE POLIO IRUS VACCINES

27. LARGE-SCALE PRACTICAL TRIALS AND USE OF
LIVE POLIOVIRUS VACCINE IN THE USSR
PROFESSOR V. M. ZHDANOV
with the participation of
PROFESSOR M. P. CHUMAKOV AND PROFESSOR A. A. SMORODINTSEV
USSR Academy of Medical Sciences, Moscow, USSR
DR. ZHDANOV (presenting the paper): Since
the text of my report* was distributed among
the participants of the Conference, there is no
need for me to read it. I shall therefore only
try briefly to convey its content, and then mention
some additional considerations on the problem.
I have been encouraged to do so both by
the interesting remarks made by Dr. Stuart-
Harris and by Dr. Paul's profound and wellpresented
report.
The problem of mass immunization against
poliomyelitis-a comparatively rare but severe
disease-has suggested some specific requirements
for the use of the vaccine, namely:
1. Complete safety of the preparations;
2. The practically full irreactivity of vaccination;
3. Sufficiently full efficacy of the vaccine, in
the sense of prevention of the disease;
4. The possibility of a sharp reduction of
poliovirus circulation;
5. Low cost of preparation, facility of production,
and availability to the population;
6. A suitable and convenient method of administration.
The Salk vaccine meets the first three requirements
mentioned above. Therefore, once its production
was organized, an intensive offensive
against poliomyelitis was started. However, soon
thereafter, some deficiencies in this generally
good preparation became evident.
Although it produces in individuals a specific
defense against the paralytic disease, immunization
with the Salk vaccine does not prevent the
circulation of wild poliovirus strains becatse
the intestinal-tract cells remain susceptible to
them. Moreover, about 20 to 30 per cent of vaccinees
remain unprotected against the paralytic
disease, and the immunity decreases at a significant
rate during subsequent years.
* For complete text, see pp. 578-587.
These deficiencies became dramatically known
soon after the first triumphant years of the
Salk vaccine, when severe epidemics of poliomyelitis
appeared in Israel, Hungary, and some
localities of the USA, despite the large percentage
of vaccinated persons in those countries.
As a result of research work done by Sabin,
Koprowski, Cox, Smorodintsev, Chumakov, and
others, a basis for production and field trials of
live poliomyelitis vaccine derived from attenuated
virus strains was established, and this vaccine
appeared to satisfy the six principal requirements
mentioned above. Its particularly
important property is the capacity to produce
in vaccinees a degree of immunity which not
only ensures the individual defense of the vaccinees
but also renders the intestinal-tract cells
insusceptible to the virus, thus sharply reducing
the circulation of wild polioviruses among the
population.
Other important advantages of this vaccine
are its low cost, its availability to the population,
and its simple method of administration,
i.e., by the oral route, as compared to injections
of the Salk vaccine.
The various stages of research and practical
use of the live poliomyelitis vaccine in the USSR
are well known to you. They constitute a good
example of cooperation between scientists of the
USA and USSR, namely, A. Sabin, M. Chumakov,
A. Smorodintsev, and their associates.
These stages were:
Research work done by A. Smorodintsev
(1957-1958) and M. Chumakov (1958) and
their associates on the safety of Sabin's attenuated
strains, and carefully carried out mass
experiments in children;
First field trials (1958) in sorne tens of
thousands of the population;
Mass immunization of the population early
in 1959 in the Baltic republics of Esthonia,
Latvia, and Lithuania;
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