LIVE POLIO IRUS VACCINES

288
Efficacy-Laboratory Evidence
288 Efficacy-Laboratory Evidence
and by heel puncture at approximately monthly the capacity of human beings to serve as hosts
intervals up to four to six months after birth. for poliovirus is well developed up to three
Readministration oa Attenuated Virus. Fourteen
months before term birth. Evidently the in-
infants were given a second feeding of 105- 7 testinal lymphoid or epithelial tissue in which
TCID 5 0 CHAT three to five months after the poliovirus may multiply is "mature" enough to
first administration; four stool specimens were
collected at home during a two-week period after
readministration of the virus.
General Observations. As a preliminary trial,
support virus growth in premature infants. Consequently
the speculation that the failure of fullterm
infants to become infected with attenuated
virus is somehow related to biologic immaturity 3
five infants were given attenuated poliovirus and
were found to excrete virus without symptoms
and without evidence of transmission of the virus
was not supported. We inferred that some transitory
phenomenon lasting about two months occurs
sometime after birth to induce resistance to
to other infants in the nursery. Additional infants
were then given CHAT virus.
infection in a proportion of vaccinated full-term
infants, an inference supported by subsequent
Ninety per cent of the infants were infected
studies.' The converse interpretation is that the
intestinally, as evidenced by repeated isolations
nf Tyve. 1 nnlinvirii from fecal snecimens begin-
susceptibility of newborn infants to attenuated
ning within a day of feeding (Table 1). Only 10 virus is transitorily lost in some infants.
per cent of the infants were not infected.*
TABLE 1. INTESTINAL INFEECTION AND ANTIBODY fants had transplacentally acquired poliomyelitis
RESPONSE WITH C] HAT VIRUS antibodies before vaccination. The findings in
Intestinal
Infection
Infants
Infected 90% (44)*
Not Infected 10% (5)
Transplacentally Acquired Antibodies and Intestinal
Infection. Almost all the premature in-
these infants (Tables 3 and 4) allow us to be
Antibody Response
Positive Negative increasingly certain that both resistance to intestinal
infection with attenuated poliovirus and
failure of antibody response are unrelated to the
o 100% (5) presence of transplacentally acquired antibodies
in the infant's circulation. The percentages of
All Infants 100% (49) 47% (14) 53% (16) infants that were infected, as well as the mean
duration of excretion, were neither diminished
* Number of infants in parenitheses.
by high pre-vaccination titers nor increased by
However, despite a wellof
this sort an antibody reslponse was frequently
established infection
low cord-blood titers (Table 3).
Transplacentally Acquired Antibodies and Imnot
observed (Table 1).
excreted poliovirus only 56
nificant antibody response;
Among infants who
per cent had a sigthe
significance of
mune Response. The antibody response that fol-
lowed administration of attenuated virus did not
appear clearly related to the presence or the
this lack of response despiite infection will be
taken up later.
titer of such congenital antibodies, again, within
the limits of the titers of maternal antibodies that
Birth Weight and Excretion of Virus. There were encountered, as indicated in Table 4.
was no notable relation (Ta ble 2) between birth There is, however, a suggestion of a trend that
weight and the duration of e: xcretion of virus. Ex- higher titers of maternal antibodies may interfere
cretion regularly began soon after administration
with the development of active antibodies.
of the vaccine and continueed for an average of
three or four weeks regardlIess of tha size of the However, as we test the equivocal group, shifting
them into the positive or negative groups, we
child.
The frequency of infectio n (Table 1) and the have been able to evaluate additional data. There
lack of relation to birth wreight indicated that is no clear-cut trend. If there is an effect, it is
difficult to discern within these levels of anti-
from one of thes e
* Coxsackie B-5 virus was isodlated
infants.
bodies.