LIVE POLIO IRUS VACCINES

DISCUSSION
CHAIRMAN LÉPINE: Thank you, Dr. Voroshilova.
The paper is open for discussion.
data as Dr. Smadel mentioned will be collected
during future years.
DR. SMADEL: It goes without saying that our
Russian colleagues deserve our congratulations
on the many scientific accomplishments with live
polio vaccine, certain of which they have reported
here today. I should like to comment particularly
on the matter of the Tashkent outbreak and to
refer to Figure 11 of the booklet made available
to us by our Russian colleagues and entitled "On
Mass Oral Immunization of Population in the
Soviet Union against Poliomyelitis with Live
Vaccine from A. B. Sabin's Attenuated Strains,"
Moscow, 1960. This figure shows the difference
in rate of paralytic disease among those who were
vaccinated and among the unvaccinated portion
of the population.
I am in agreement with the comments of Dr.
Chumakov and his associates regarding the possibility
that the prompt and appreciable drop in
paralytic disease among the vaccinees during
the period when the rate in the non-vaccinated
continued to rise might represent interference by
the attenuated virus with the wild virus.
I should hope, as a scientist and as a public
health officer, that the opportunity may arise in
the next year for similar studies to be undertaken
not only by our colleagues in the USSR but by
scientists in other parts of the world. It is
important that we learn whether we can depend
on the interference phenomenon to work for us
instead of against us. This week we have heard
more about wild enteroviruses in the intestine
that interfere with implantation and growth of
attenuated polio strains, thus hampering the development
of immunity. Tashkent may have
provided the first example of a "good" virus
driving out of a "bad" virus in the population
suffering an epidemic of polio.
CHAIRMAN LÉPINE: Dr. Voroshilova, do you
wish to comment on this?
DR. VOROSHILOVA:
of Dr. Chumakov.
I spoke only as the tongue
We may expect that such
429
DR. VERLINDE: I wish to comment very briefly
on the slides that Dr. Voroshilova has shown
with regard to the incidence curves of paralytic
poliomyelitis before and after the administration
of the live vaccine.
I should like to say that I too very much admire
the studies that have been undertaken in the
Soviet Union. Let me also state that I personally
believe in the epidemiological effectiveness
of the vaccine. But before drawing definite
conclusions with regard to the epidemiological
effectiveness, I think that we can make a judgment
only after more years have passed. In
this respect, may I remind you of one of the
slides I showed yesterday in which one could
see that in the Netherlands, after the epidemic
year 1956 (in which a high incidence of poliomyelitis
occurred), the incidence gradually decreased
during the years 1957 and 1958 and
that an extremely low incidence was reached
in 1959.
If we had administered live poliovirus vaccine
on a very large scale, this curve might perhaps
be an excellent example of the epidemiological
effectiveness of the vaccine. However, we have
not administered the vaccine on such a scale.
DR. CHUMAKOV (through an interpreter): Dr.
Verlinde believes that several years will elapse
before we can give a positive answer. I am not
of that opinion. Our experiments in the Soviet
Union show that the mass immunization-and I
refer to the first part of this year-has already
produced such a sharp decrease in the incidence
of the disease that there is no doubt that this is
connected with the vaccination.
I should add that we have shown only a few
examples, but this is confirmed in all the areas
where we have applied mass immunization. Everywhere
we have achieved the sharpest decrease very
successfully. Without exception, there has been
no instance in any area where we have conducted
mass immunization on a large scale that