LIVE POLIO IRUS VACCINES

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TOPIC III. EFFICACY. (B) FIELD EVIDENCE
(continuation)
22. FURTHER OBSERVATIONS IN CONJUNCTION WITH THE FIRST
FIELD TRIAL WITH LIVE POLIOVIRUS VACCINE IN
CZECHOSLOVAKIA. EPIDEMIOLOGICAL STUDY
VILÉM SKOVRÁNEK, M.D.
Ministry of Health, Prague
DR. SKOVRÁNEK: At the First International
Conference on Live Poliovirus Vaccines last
year, I had the opportunity to report on the first
results of the extensive work of Czechoslovak
scientists, compiled during the first field trial
with Sabin's vaccine, which was conducted in
a defined part of our country in approximately
140,000 children aged two to eight years, who
had been previously vaccinated three times,
intradermally, with Salk's vaccine.l
The purpose of this paper is not merely to
report on further results obtained in the course
of the above trial, but also to discuss from a
somewhat broader aspect, the reasons why we
(including myself as the responsible public
health service officer*), took the decision to use
the live vaccine in the spring of this year on a
very large scale for mass vaccination of the
entire child population aged two months to 14
years in the entire territory of our Statet. The
* According to Czechoslovak regulations it is within
the competence of the i"Chief Hygienist," i.e., the
Chief Medical Officer of the sanitary and epidemiological
services, to decide on any type of special mass
vaccinations, if justified on epidemiological grounds.
t The mass vaccination program with live vaccine
produced in Czechoslovakia from Sabin's strains, and
partly supplemented by Types 2 and 3 prepared in the
Soviet Union, was implemented in two stages. Type 1
was administered between 28 March and 11 April
1960; a mixture of Types 2 and 3 was administered
between 2-11 May 1960.
In four regions, where a portion of the child population
had received live vaccine during the first field
trial in the winter of 1958-1959, a single dose of trivalent
vaccine was administered between 11-20 April of
507
short time which has elapsed since this extensive
vaccination program was completed, less
than one month ago, permits me so far to say
only that nothing remarkable occurred in the
course of this extensive vaccination, which would
arouse the attention of the health services and
which could be interpreted as having any causal
relationship with the vaccination. We were
thus able to confirm, on more than the 20-fold
number of vaccinated individuals, the conclusion
reached during the first field trial, i.e., that
vaccination with the live poliovirus vaccine from
Sabin's strains is safe.
The main purpose of my paper, as mentioned
before, is to explain the reasons why, after
analyzing the results compiled in 1959, we took
the decision to carry out this extensive mass
vaccination.
Before evaluating the 1959 results, I should
like to say, by way of introduction, that during
that year the vaccination program with the live
vaccine was not extended further. This gave us
an opportunity to conduct observations throughout
the year in strictly defined areas (four orally
vaccinated regions-Ustí, Liberec, Jihlava, and
Ostrava; and in one region-Plzeil, where a
fourth dose of Salk's vaccine was administered
this year to all children aged from two months to 14
years (including children already vaccinated in the
first trial). A total of about 3,500,000 children aged
from two months to 14 years (about 94 per cent of the
child population or about 26 per cent of the entire
population of Czechoslovakia), was vaccinated by
both of the above-mentioned methods.