LIVE POLIO IRUS VACCINES

348
Efficacy-Laboratory Evidence
taminated with Type 1 vaccine virus*. This
would have the effect of making some of the first
feedings in the monovalent group in reality a
bivalent feeding composed of Types 1 and 2 vaccine
virus. Therefore, even though the results in
* A total of 113 participants received the monovalent
vaccine. After the Type 2 feeding, Type 1
virus was isolated from 32 specimens; Type 2 was
isolated from 11 specimens, and 70 were negative for
virus isolation. A single Type 2 isolation occurred
in the placebo group. After the Type 1 feeding, there
were 43 isolations of Type 1, two of Type 2, and a
single Type 3! The placebo group yielded one Type
1 and two Type 2 's. Type 1 virus was thus appearing
following a Type 2 feeding when it should have
been absent. The negative results in the placebo
group appeared to exclude a laboratory "pick-up"
or an adventitious, wild Type 1. Additional laboratory
studies eventually revealed that Type 1 virus
was present in four out of the four vials of Type 2
vaccine that were subjected to such a search. The
concentration of the Type 1 virus found was of the
order of 5 TCD 50 per ml.
The Lederle Laboratories reported confirmation of
the above results, but they also reported that the unfilled
pool of Type 2 vaccine was free of Type 1
virus.
Lederle Laboratories, on review of their own
protocol kept at the time that the vaccines were being
readied for shipment to Minnesota for the Grove
East study, reported to the State Health Department
the series of events that explained how this incident
occurred. The filling machine first was used to fill
placebo vials. Then vials were filled with monovalent,
Type 1, vaccine with the same machine.
Because of the pressure of time, the machine was
flushed through with placebo instead of being sterilized
and used to fill vials with Type 2 vaccine; the
first 200 ml. being discarded. A different machine
was used for the Type 3 vaccine.
the monovalent group are within the compass of
expectation; though they do not appear at all
bizarre; and though they are in line with previous
experience, still, strictly speaking, one cannot say
that a comparison between the effects of monovalent
versus trivalent vaccine with respect to
inducing antibodies to Types 1 and 2 poliovirus
has actually been consummated. The comparison
with respect to Type 3, however, is completely
valid.
Another way to gauge the effectiveness of the
vaccine, either monovalent or trivalent, is to
measure the degree of success attained in converting
to triple antibody positives those, who
before ingesting the vaccine, lacked demonstrable
antibody to one or more poliovirus types. The
data to show this type of effect is entabled for
the monovalent group, children and adults, in
Tables 7a and 7b. Tables 8a and 8b are similarly
applicable to those who received the trivalent
vaccine. A summary of these tables
appears as Table 9. From this table, it appears
evident that conversions to triple positive are
better accomplished in children by the monovalent
vaccine. On the other hand, to accomplish
the same purpose in adults, the trivalent
vaccine appears better. The efficiency of the
trivalent vaccine in generating triple positives is
the same for both adults and children although,
as has been mentioned, the monovalent vaccine
is better for children.
TABLE 7A. ANTIBODY STATUS, BEFORE AND AFTER VACCINATION, OF THE 23 ADULTS LACKING POLIO-
VIRUS ANTIBODIES BEFORE INGESTION OF TRIVALENT ORAL POLIOMYELITIS VACCINE, GROVE EAST, 1959
Number of Persons Negative*, by Poliov~us Type
__Pree- eedi Post-fe edng
Total No. No. of Complete
Negative No. of of Conversions to
to Type Persona 1 2 3 1 and 2 1 and 3 2 and 3 1, 2 and 3 Negativeas Triple Positive
1 4 2 2 2
2 2 1 1 1
3 10 1 1 9
1 and 2 O O O
1 and 3 4 1 1 3
2 and 3 1 O 1
1, z, and 3 2 1 1 1
Totals 23 2 1T E 1 17
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* Titer of