LIVE POLIO IRUS VACCINES

Virologic, Serologic Investigations of Immunization With Sabin's Strains 243
TABLE 4. ABSENCE OF POLIOMYELITIS ANTIBODY IN CHILDREN OF DIFFERENT AGES BEFORE VACCI-
NATION (Moscow REGION, 1959)
NUMBER OF SERA WITHOUT ANTIBODY TO
TRIPLE-NEGATIVE
SERA
No.
20
43
76.9 9
31.4 11
86.0
60.6
13.8
5.9
15.4
19.0 2
48.8 85
4.8
20.0
demic season of 1955 when children, at that time
one to three years old, were infected to a greater
extent than older children. In the age group of
10 to 15 years, 4.8 per cent of the children were
triple negative, 28.6 per cent had no Type 1 antibody,
11.9 per cent no Type 2, and 19.0 per cent
no Type 3 antibody (Moscow region, Table 4).
Serological investigations were carried out
mainly by pH neutralization tests in tubes or insulin
vials. A portion of sera was tested by the
cytopathogenic neutralization test. Besides, some
sera were tested in parallel by complementfixation
tests and precipitation tests in agar gel
on slides. Serum specimens from each child
(two to six specimens) were always examined
simultaneously in one test.
RESULTS
Examination of pre-vaccination stool specimens
revealed the presence of extensive virus carriage
of nonpoliomyelitis enteric viruses in children
from children's homes L. and R. in the summer
(about 50 per cent of the children, Table 7).
Virologic examination of stool specimens collected
after immunization with live trivalent vaccine
demonstrated vaccine virus excretion in
children's homes L. and R. (summer) during
the first month after vaccination in 70 per cent
of the children, and in children's homes No. 5
and No. 10 (winter) in 96 per cent of the vaccinated
children (Table 8).
During the first month after vaccination,
gradual decrease of excretion rate was observed
from the first to the fourth week (Table 9). During
the second post-vaccination month vaccine
virus excretion continued to decrease, but more
than half of the vaccinees were still excreting
vaccine viruses (Table 8).
Establishment of vaccine viruses depended also
on the age of the vaccinees. In children under
three years, vaccine viruses were found to establish
with greater frequency and for longer periods
than in older children (three to seven years,
Table 10).
By frequency of vaccine virus excretion according
to types, the first place was occupied by
Type 2 vaccine virus, the second by Type 1
vaccine virus, and the third by Type 3 vaccine
virus, observations being made in children vaccinated
with trivalent live vaccine. Frequency
of Types 1 and 2 vaccine virus excretion was
approximately the same, while Type 3 vaccine
virus was excreted much less frequently (Tables
11-14).