Report on Poliomyelitis Vaccine Produced by the Cutter Laboratories

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toinactivation. Distribution of vaccine containing infective amounts rn
of live virus could have occurred if the vaccine was inadequately in- - "
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activated or if contamination occurred before withdrawal of vaccine $_
for the final safety tests, but in either case only if the final safety
tests failed to demonstrate the presence of live virus. If contamination with virus occurred after the vaccine had been sampled for the
safety tests, then the presence of live virus would have gone undetected.
The possibility of contamination
The equipment, the physical arrangements and the routine handling
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procedures of the Cutter Laboratories were checked in detail to deo
termine if deficiencies in them might have led to contamination.
Nothing was found to indicate that the infective amounts of live virus
in Cutter vaccine were attributable to contamination.
The possibility of inadequate inactivation
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In the production process the final safety tests on the trivalent
pool (a mixture of the three types of virus) constituted the final check o
against the release and distribution of an individual lot of vaccine
which might have contained an infective amount of live virus if
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inactivation had been inadequate. Prior to May 27, inadequacy of
inactivation was not unusual in the experience of several of the
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Imanufacturers. In addition, there were then fundamental weaknesses in CD
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the safety testing procedures which failed to assure what is now
believed to be a satisfactory degree of sensitivity.
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