LIVE POLIO IRUS VACCINES

148
Saf ety-Field Evidence of Saf ety
148 Safety-Field Evidence of Safety
quent in children below 6 years of age and in sulted in abortive infection.
the low-titer group. Overall, spread was clearly
more extensive in the more heavily seeded Franklin
community (70 per cent of low and 32 per
cent of high-titer children) than in Morgan City
(33 and 25 per cent, respectively). All told, 28
low-titer children developed alimentary infection
and, of these, all but nine manifested significant
antibody response. In the high-titer group, 17
were observed to excrete virus, but only four
evinced antibody response.
Wide variations were observed in duration of
fecal virus excretion. In the vaccine-fed children,
the mean observed excretion was 22 and 9.7 days
for the low and high-titer groups, and the range
was, respectively, from 1 to 63 days and from 1
to 31 days. Among the placebo-fed children, the
corresponding figures were 17 and 6.8 days for
the means, and from 1 to 37 days and from 1 to
34 days for the ranges. For the vaccine-fed children,
Fig. 3 indicates the relation of the postfeeding
antibody titer to that observed prefeeding
and also, on a rough qualitative basis, to the fact
and duration of fecal excretion of virus. Of those
actually observed to shed virus in the feces, abortive
excretion for only one or two days, indicated
by the circle with a central dot, was observed in
5 of 53 low and 14 of 40 high-titer children. Similar
data for the placebo-fed children are presented
in Fig. 4 which indicates the much greater
frequency with which contact transmission re-
Such was observed
in 7 of 28 infected low-titer children and in 9 of
17 in the high-titer group. Of special importance
is the fact that these abortive infections were
commonly associated with failure to develop a
significant increase in antibody titer. Finally,
in agreement with our previous observations, well
established alimentary infection also failed to
elicit a significant response in children with very
high initial antibody titers.
The pattern of vaccine virus spread. It is difficult
to generalize about the pattern of spread
within the placebo-fed household units. In one
Franklin and four Morgan City families, the entire
household episode of P3 virus infection consisted
of fecal excretion by only one child detected
on only one day (2 in high and 3 in low-titer
children), despite the availability of from 5 to 8
other children in each family, including a total
of 11 with low and 19 with high titers. At the
other extreme, all or all but one child became infected
in six families, three in each community.
When more than one child became infected, the
interval between onsets of viral excretion varied
widely; several children might begin excretion
within a few days with others beginning excretion
two or more weeks later. In one household,
in which all of six children became infected, the
onsets of excretion were on days 28, 28, 29, 46,
60, and 60 of observation.
What might be ternied the week-by-week volume
TABLE 3.
FECAL EXCRETION OF TYPE 3 POLIOVIRUS AND ANTIBODY RESPONSE IN PLACEBO-FED
CHILDREN, BY AGE, PRIOR HOMOLOGOUS
ANTIBODY TITER AND RESIDENCE
Neighborhood Age Prior titer 1 :