LIVE POLIO IRUS VACCINES

510
Efficacy-Field Evidence
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FIc. 2. Poliomyelitis morbidity in Czechoslovakia, 1959.
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the attenuated viruses, fed to part of the population,
did not cause (during the observation
period which so far is one year) an increase in
the morbidity. In poliomyelitis, it is, of course,
very difficult to rule out whether a certain reduction
of the morbidity in certain parts of the country
is not due to the commonly observed local
variations; nevertheless, a more detailed analysis
of the results in the four orally vaccinated regions
gives the impression that some differences
exist, particularly as regards the age groups of
vaccinated children (Table 2 and Fig. 3). The
table indicates that in the group of children aged
two to eight years in 1958 and three to nine years
in 1959, respectively, there was no case of poliomyelitis
among vaccinated individuals; in nonvaccinated
individuals, the morbidity was lower
than in other regions; this can be explained by
contact transmission of attenuated viruses.
As far as the effectiveness of the commonly
used doses of inactivated vaccine in the remaining
parts of the country is concerned, certain
differences were observed in the specific
age incidence among vaccinated and non-vaccinated
individuals in 1959 (Fig. 4).
In general, the analysis of the poliomyelitis
incidence in 1959 should be no special cause
for alarm, except for the increased morbidity
in Slovakia. On the contrary, the relatively low
general morbidity and the large number of vaccinated
individuals could, without more detailed
investigations, lead to a favorable evaluation of
the situation.
2. Results of Seroimmunity Investigations.
The low morbidity figures, particularly in the
western part of the country, contrast considerably
with the results of repeated investigations
of the seroimmunity of population groups and
individuals subjected to different methods of
vaccination.
In view of the fact that a considerable portion
of our paper last year was devoted to the methods
and main results of these investigations,
and because they are the subject of a separate
report (Dr. Vonka) *, I should like to refer
* See pp. 228-239.