LIVE POLIO IRUS VACCINES

Capacity of Live Attenuated Polioviruses to Cause Human Infection 179
prolonged periods, some lasting seven weeks.
Poliovirus infections are shown by the black
stripes. Coincidentally, many enterovirus infections
were present and these are shown by various
kinds of shaded stripes.
And, as the final group in this series of diagrams
the same general situation is shown for the
67 exposed siblings within these same 48 families
(see Figures 7 and 8).
Figure 7 illustrates Type 1 infections in the
population of 67 siblings (under the age of five)
who were members of those families in which intrafamilial
exposure to an infected vaccinee occurred.
Fifteen siblings possessed Type 1 poliovirus
antibodies prior to the administration of
the first dose of triple vaccine. Eleven negative
siblings converted during the 9-week-period of
observation-a rate of 21 per cent. Of those 15
children already possessing antibodies to Type
1, 5 showed a fourfold rise associated with reinfection
as indicated by the dark area in the
lower right-hand corner.
Figure 8 similarly illustrates Type 3 infec-
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tions among 67 siblings as a result of intrafamilial
exposure. Forty of these siblings
possessed antibodies to Type 3 poliovirus before
vaccine was introduced into the family, and of
these, 18 became re-infected. Of those 27 who
lacked antibodies at the onset, 15 converted.
Non-poliovirus Enteroviruses. The degree to
which the children in this study were harboring
non-poliovirus enteroviruses during the prevaccinal
period of one week appears in Fig. 9.
In Figure 9 the age-specific rates are shown
at which participants in this trial excreted polioviruses
and non-poliovirus enteroviruses prior to
the first administration of vaccine. Our impression
is that the impact of the non-poliovirus enteroviruses
upon the poliovirus responses in the
vaccinees, or the actual degree of interference
which they exerted in this trial was appreciable
but not great. When a comparative rate analysis
was made to determine whether those children
harboring such enteroviruses at the beginning of
the trial had a higher failure rate than tlihose without
enteroviruses, there was evidence that, as far
2nd Vac.
Siblings
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FIG. 8