LIVE POLIO IRUS VACCINES

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Safety-Field Evidence of Safety
Safety-Field Evidence of Safety
Because cord blood had not been obtained from
either of these infants, it could not be determined
whether the pre-feeding antibody titer present
for Type 2 was Salk-induced or the result of passive
transfer from the mother.
Calculation of Antibody Titer Response to
Vaccination in the Young Infant. Because techniques
for antibody titer determinations do not
differentiate between the sources of antibody, it
is necessary, if the effect of vaccination in the
Vaccine. Refer to preceding section dealing young infant is to be known, to be able to determine
with the vaccination responses of pregnant
at any age the amount of circulating
women.
Administration of the Vaccine. Each of the
passively transferred maternal antibody that remains.
infants was fed several drops of the vaccine at a
time from an eye dropper until 0.5, 1.0, or 2.0 cc.
were given. The vaccine was placed on the back
of the tongue and followed in most instances by
a feeding at the breast or bottle. With few exceptions,
all newborns were vaccinated just prior
to discharge from the newborn nursery.
Of the 90 newborn infants who returned one or
more times for blood drawing after vaccination,
nine had received 0.5 cc. of lot No. 800 and three
0.5 cc. of a mixture of lots No. 7-1231-121, No.
7-1232-216, and No. 7-1233-318. Thirty-four had
received 1.0 cc. of lot No. 801-2; nine, 1.0 cc. lot
No. 800; and 15, 1.0 cc. of lot No. 801. Of the
20 newborns receiving 2.0 cc. of vaccine, nine received
lot No. 804-A; one, lot No. 801; and 10,
lot No. 801-2.
Of the 47 older infants with follow-up antibody
studies completed, 11 received 0.5 cc. of
vaccine. Of these, six received lot No. 800 and
five a mixture of lots No. 7-1231-121, No. 7-1232-
216, and No. 7-1233-318. Five received 1.0 cc. of
vaccine. Of these, four received lot No. 801-2
and one, lot No. 800. Thirty-one infants were
fed 2.0 cc. of lot No. 804A.
Blood Collection. Cord blood was colleatel at
the time of delivery from the infants in both
study groups to determine the titer of the passively
transferred maternal antibody. All other
blood samples were obtained by jugular or antecubital
venipuncture. In the newborn group
blood for antibody determinations was drawn at
the median ages of 45, 186, and 375 days. In the
older age group, a blood sample for antibody
determination was taken at the time of feeding
of the vaccine and again at about age six months
and age 12-18 months. All blool samples were
aseptically collected without an anticoagulant.
Laboratory. Refer to preceding section dealing
with the vaccination responses of pregnant
women.
A previous study -1 of antibody transfer from
mother to newborn infant and follow-up of the
infant during the first year of life has shown
that the poliomyelitis antibody disappears from
the newborn at a uniform rate with a half-life
value of 37 days. This is shown graphically in
Fig. 2. This half-life value was found to be the
same whether the maternal antibodies were induced
by injections of Salk vaccine during pregnancy
or whether they were naturally occurring.
Other substantially different half-lifes for pla-
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1 I I I i
Rate of Decrease of Passive Polio
Antibody Titers in Infants
\ ("Half-life" Approximately 5 Weeks)
\l
10 20 30 40 50 60
Time in Weeks
FIG. 2
centally transferred poliomyelitis antibodies have
been reported. 6 12' To determine if the 37 day
half-life was sufficiently accurate to apply to our
studies a second blood specimen was taken at
the time of vaccination in the older infant group.
The antibody titer of this blood specimen paired
with the cord blood was determined and plotted
on a correlation square against the residual passively
transferred maternal antibody titer as
calculated from the cord blood titer using the