LIVE POLIO IRUS VACCINES

Live Poliomyelitis Vaccine-Small-Scale Trial in Isolated Island Community 541
TABLE 7. OCCURRENCE OF A FOUR-FOLD OR GREATER INCREASE IN TYPE 2 AND TYPE 3 ANTIBODIES
IN PERSONS WITH AND WITHOUT A CORRESPONDING INCREASE IN TYPE 1 ANTIBODIES
and that no Type 2 or Type 3 viruses could be
isolated, the Type 2 and 3 antibody increases
may be regarded as heterotypic antibody responses.
Effect of oral administration of all three types
of live poliovirus in 1959. When the second part
of the trial was initiated in March 1959, blood
samples were obtained from 201 persons. Among
41 persons from whom blood samples were obtained
and who had been fed live Type 1 vaccine
in 1958 there were no triple negatives and
no persons negative to Type 1, but nine of these
41 were still negative to Type 3 only, and three
to Types 2 and 3. Among the remaining 160
who had not received live Type 1 vaccine, three
were triple negative, and 34 were negative to
one or two types.
Six weeks after the last feeding of Type 3,
13 persons excreted Type 3 virus. Only four of
these 13 were negative to Type 3, and only one
was triple negative before feeding. However.
only one of the remaining nine had a titer exceeding
1:4. No type 1 or Type 2 virus could
be isolated (Table 8). The isolated strains have
not been tested for monkey neurovirulence.
Of those who received the vaccine and from
whom appropriate serum samples were obtained,
a conversion from seronegative to seropositive
was seen in all but two of those previously vaccinated
with live Type 1 vaccine and in all
except one of those not previously vaccinated
with live Type 1 vaccine (Table 9). The numbers
are extremely small, but on the basis of
them, the conversion rates were 93, 93, and 96
per cent for Types 1, 2, and 3 respectively.
Combined effect of the various vaccination
schedules. At the end of the trials there were
109 persons from whom all six blood specimens
and all five stool samples had been obtained
and who had participated in the whole vaccination
program. Twenty-nine of these persons had
received live Type 1 vaccine in 1958 and 80
had not. All of them had received two injections
of inactivated vaccine in 1958 and all three
typcs of live vaccine in 1959.
This selected group, including 21 children
under 10 years of age and 88 persons over 10,
gives a fairly good picture of the changes in
the immunity status of the population of Sottunga
(Figs. 4-8). Thus, after the last feeding
there were among the children under 10, most
of whom were initially triple negative, only one
negative to Type 2 and one negative to Type 3.
The over-all increase in measurable antibodies
is shown by the change in geometric mean titer.
A somewhat similar picture is obtained for
the 88 persons over 10 except that among those
not fed virus there seems to be an increase in
Type 3 antibodies which is difficult to explain.
If, however, as previously mentioned, it is
assumed that no Type 3 virus was present, the
increase may be explained as a heterotypic response
to circulating attenuated Type 1 virus.
The combined effect of the various vaccination
schedules may also be studied by estimating the
total number of negatives to any of the three
types during the trial (Table 10).
Thus, of the 196 persons tested at the last
sampling in June 1959, only three persons remained
negative to Type 1 only, three persons