LIVE POLIO IRUS VACCINES

Large-Scale Practical Trials, Use of Live Poliovirus Vaccine in USSR 587
Poliomyelitis in the Lithuanian SSR
Reduction in the period June to December 1959 inclusive
100
90
80
70
Compared with the average over many years 212:17=12.5
Compored with 1955 411:17=24.2
Compared with 1956 247:17=14.5
Compared with 1957 124:17=7.3
Compared with 1958 264:17 15.5
v. 60
o 50
o
Z 40-
30-
20
10
16
The
The
vertical axis of the graph shows the
number of cases.
horizontal axis shows the months from
June-December 1959.
0 1 959 fl 'CZ 1 The broken line is the average number
cases over many years.
Mos. VI VII VIl IX X XI XII
DIAGRAM 2.
Poliomyelitis in the Lithuanian SSR. Reduction in the number of cases in
1959 after immunization with the live vaccine.
of
tions, carried out in carefully controlled surveys,
established that mass immunization with live
poliovirus vaccine is highly effective from an
epidemiological point of view.
In the Esthonian, Lithuanian (see Diagrams
1 and 2), and Latvian Republics, where mass
vaccination had been finished in the main before
1 June 1959, a sharp reduction in morbidity
(down to single cases) was achieved in the second
half of the year. This can be considered
as a proof of the effectiveness of the live vaccine.
In the Moscow Oblast, the City of Karaganda
and some other regions, where oral administration
of trivalent vaccine was begun at the height
of the seasonal rise in morbidity, a considerabre
reduction was nevertheless noted in the number
of cases among vaccinated persons compared
with the number among the unvaccinated (between
9.5 and 10.8-fold).
It is important to note that single-stage mass
vaccination with trivalent live vaccine carried
out during a poliomyelitis epidemic in Tashkent
in 1959 fully confirmed the possibility of seriously
reducing the epidemic incidence of poliomyelitis
in five weeks as a result of the interference
of the vaccinal virus with the epidemic
process and the increasing level of immunization
of susceptible groups.
In conclusion, a feature worthy of comment
is the fruitful international cooperation on the
problem of the live poliovirus vaccine which has
grown up between scientists in the USA, the
Soviet Union, Czechoslovakia, Hungary, the
German Democratic Republic, the People's Republic
of China, Bulgaria, etc. on the basis of
a wide exchange of scientific information, personal
meetings, the exchange of the results of
research work and mutual support.
What has been done so far is undoubtedly
only a very promising beginning to regular inter-