LIVE POLIO IRUS VACCINES

584
Efficacy-Field Evidence
medical establishments on a strictly voluntary
basis. The public was drawn into the work to
the greatest possible extent by means of extensive
health education and propaganda, use being
made of the press, radio, television, newsreels,
talks, leaflets, etc.
In the areas covered by the campaign, consultative
teams of experienced physicians were
set up for a thorough investigation of all cases
of disease of the central nervous system which
might give rise to a suspicion of poliomyelitis.
In the Esthonian and Lithuanian SSR Epidemiological
Bureaux were established for detecting
and investigating all cases of poliomyelitis.
In addition, travelling groups of consultants
were organized in Esthonia, Lithuania, the Moscow
Oblast, the city of Karaganda, the Sverdlovsk
and Orenburg Oblasts, etc. More than
1,500 vaccinated persons and persons in contact
with them were given serological and virological
examinations. The laboratory diagnosis of cases
of poliomyelitis in areas covered by the campaign
was considerably extended and consolidated
in the Baltic republics, Tashkent, Alma-
Ata, Karaganda, Moscow Oblast, etc. All this
has made it possible considerably to improve
the organization of mass vaccination, to provide
for careful observation to be kept over the vaccinated,
to intensify the diagnosis of poliomyelitis,
and to ensure the fullest possible
registration of all cases of illness during and
after administration of the vaccine. In children's
establishments in a number of places long-term
observations of the temperature and state of
health of the vaccinated children and children
in contact with them were carried out.
We laid down as our main principle in organizing
oral administration of live anti-poliovirus
vaccine that it should be on a mass scale and
simultaneously carried out throughout the territory
of a whole rayon, city or oblast in order to
establish extensive immunity among the population
in the shortest possible time and to reduce
to a minimum the possibility of lengthy circulation
among susceptible persons of any
strains of poliovirus and to eliminate the possibility
of an increase in their virulence through
serial passage in children.
The first results of the study and mass use
of live poliovirus vaccine made from Sabin
strains in the USSR in 1959 were summed up
in Report No. 2 of the Institute for the Study
of Poliomyelitis of the USSR Academy of Medical
Sciences and of many Republican, Oblast,
and City Sanitational and Epidemiological Centers.*
On a basis of the extensive research carried
out in the Soviet Union by several teams of
scientists and of practical trials, the following
conclusions can be drawn concerning the most
important questions connected with live poliovirus
vaccine:
1. Harmlessness of the Live Vaccine. We may
consider as completely settled the question of
whether the live vaccine made from the Albert
Sabin strains and in the manufacture of which
certain conditions have been fulfilled, are completely
harmless and will cause no reactions.
The practical trials of the vaccine on a very
large scale have merely confirmed the fact. The
safety tests for the vaccine during manufacture
perhaps still need simplification and improvement,
but even in their present form they ensure
reproducibility of results.
The problem of reversion of the pathogenic
properties in the strains of live poliovirus vaccine
was eliminated in practice by the simultaneous
coverage of the whole susceptible population
in an oblast by a large-scale immunization
campaign, since immunity in the population
developed more quickly than could changes
in the poliovirus strains, which were thus not
given an opportunity of continuous passage. No
cases of poliomyelitis caused by the actual administration
of live vaccine made from Sabin
strains have been recorded in the Soviet Union.
The reaction-causing properties of the live
poliovirus vaccine were studied by many physicians
in the vaccination areas on the basis of the
material provided by records of complaints from
those vaccinated. In the opinion of the specialists,
under conditions of mass vaccination,
cases of the coincidence of vaccination with
symptoms of various kinds caused by other diseases
may be observed. It proved impossible
to establish beyond doubt a connection between
any complaint or symptom and the vaccine itself.
The total incidence of so-called vaccinal
reactions was very low (not more than 3 per
100,000). The question of the reaction-causing
properties of the live vaccine evidently still re-
* On Mass Oral Inmmunization of Population in the
Soviet Union against Poliomyelitis with Live Vaccine
from A. B. Sabin's Attenuated Strains, Moscow, 1960.