LIVE POLIO IRUS VACCINES

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Efficacy-Laboratory Evidence
(usually at four to five days) was a significant
finding. Similar observations have been made by
Gelfand 4 in infants fed the same lots of vaccine
at two to three days of age. It would appear that
the factor of high gastric acidity in the newborn
infant does not present a serious handicap in the
oral immunization of newborn infants, when the
larger doses of vaccine are used.
Gelfand,' working with aliquots of the same
lots of vaccine, has also observed a uniform predominance
of excretion of Type 2 virus when
trivalent vaccine is administered. The interference
with Types 1 and 3 is further substantiated
by the evidence of a predominant rise
in Type 2 antibody.
The presence of high levels of maternally transmitted
antibody had no effect on the extent of
multiplication of virus in the intestinal tract. As
indicated in Table 6 the amount of virus excreted
in the stool was essentially the same in
infants with low or high titers of maternally
transmitted antibody.
Evidence of an active antibody response was
more apt to occur in infants excreting virus than
in those with negative tests for virus in the
single stool specimens examined as shown in
Table 7. An antibody response was present in
42 per cent of 55 infants with positive isolations
as compared with 20 per cent of 30 infants with
negative isolations. It is equally important to
note that in spite of active multiplication of virus
in the intestinal tract, 58 per cent of the infants
had no evidence of an active antibody response
on the basis of the criteria that had to be adopted.
Although there was no correlation between
the titer of antibody in the cord blood and the
extent of virus multiplication in the intestinal
tract (Table 6), the reverse was true for the relationship
between antibody titer at birth with
the evidence for active antibody response at three
months. Figure 1 illustrates that antibody response
was inversely related to the titer of passively
transferred maternal antibody. The lower
the titer the higher the percentage of responses.
With an antibody titer of 1:64 or less in the cord
blood the evidence for antibody response ranged
between 55 and 77 per cent. With a titer of
1:128 to equal or greater than 1:1024, the percentages
dropped from 33 to 9 per cent.
The absence of evidence of an antibody response
in an infant with a high titer of antibody
in the cord blood does not necessarily mean lack
of active antibody production. It is evident that
when the amount of antibody produced by a
newborn infant is less than half the residual
maternally transmitted antibody, its presence
would be masked. It is apparent, therefore, that
a more adequate evaluation of the active antibody
response is not possible until at least six
months or longer have passed.
CONCLUSIONS
These studies indicate that a single dose of 1
ml. of undiluted vaccine given on the day of
birth results in the establishment of intestinal
infection in about 80 to 90 per cent of the infants.
It is possible that 0.1 ml. of undiluted
vaccine may be equally effective, but a definitive
conclusion on this question will not be possible
until the final data are available. Feeding of the
trivalent vaccine in maximal dosage led to regular
multiplication only of the Type 2 virus and
only rarely of Types 1 and 3. At three months
after feeding, some children had definite evidence
TABLE 7.
CORRELATION BETWEEN POLIOVIRUS ISOLATION AND ANTIBODY RESPONSE IN INFANTS ON
WHOM BOTH TYPES OF DATA ARE AVAILABLE
VIRUS NO. OF EVIDENCE OF ANTIBODY RESPONSE
ISOLATIONS INFANTS PRESENT IN ABSENT IN
POSITIVE 55 23 (42%) 32 (58%)
NEGATIVE 30 6 (20%) 24 (80%)