LIVE POLIO IRUS VACCINES

Discussion 593
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a stool specimen was obtained early after onset,
so that the negative isolations are of some significance.
The stool was sent both to the State
Health Department and to our own laboratory.
We could not isolate any virus.
The child who had had no Salk vaccine had no
Type 1 or Type 3 antibody in both the acute and
convalescent phase sera, and only a low level of
Type 2 antibody, which did not change by the
high-avidity test.
So we have no evidence that there was a single
case of polio in Cincinnati in 1960 prior to the
oral vaccine program. And there has not been. a
single case since that time.
What we have had to investigate were three
instances of mumps, where aseptic meningitis was
suspected; but in one it was only meningismus,
because there was no pleocytosis.
We had one case of acute transitory encephalitis
in a child nine years of age who developed
fever, vomiting, convulsions, and rash one day
after feeding of the vaccine. This lasted three
days. The child, who had a pleocytosis of 180
cells per cubic millimeter of cerebrospinal fluid,
recovered completely. The child had had only
one dose of Salk vaccine, and two successive
stools, taken four and five days after feeding of
the vaccine (on which the data are already complete),
yielded no virus at all. So it was probably
a naturally immune child in whom the vaccine
virus did not multiply.
We had (on request of the physicians) to investigate
one patient suffering from acute tonsilitis,
with a temperature of 106, but with no
pleocytosis; nothing else developed and it
quickly cleared up. There was also a child with
fever for two days, with some meningismus, but
without pleocytosis. No virus was recovered from
the stools. It was a child who previously had
had five doses of Salk vaccine, and this meningismus
was 25 days after the feeding of Type 1
vaccine.
Our program at the present time obviously
calls for continued surveillance. The objective is
to see whether this extensive coverage will result
in the absence of poliomyelitis in Cincinnati for
a year.
However, I should point out that the Type 3
vaccine was given to the preschool children during
the week of 20 May, and Type 2 will be given
during the week of 20 June. The school children
will not receive that Type 2 and Type 3 vaccine
until November and December.
So if Type 2 and Type 3 polioviruses are circulating
in the community, the only barrier they
may be expected to encounter will be in the large
number of the vaccinated preschool children but
not in the school-age children, except that the
school-age children may be secondarily infected
by their preschool siblings.
It is also our intention to follow through, as
we did in Toluca, on the types of poliovirus that
will be circulating during the peak period in the
summertime, after this massive introduction of
the attenuated strains in the community, and to
see whether or not, with the amount of Type 1
virus already in the community before vaccination
and with what we have introduced, we will
find Type 1 virus during September, which is the
peak month for polio in Cincinnati.
This, then, is the preliminary report on the
mass vaccination experiment in Cincinnati, the
kind of observations that have already been made,
and what we are looking for.
CHAIRMAN VARGAs-MÉNDEZ: Thank you, Dr.
Sabin.
Does anyone else wish to present a preliminary
report on a program at present under way, or
comment on Dr. Sabin's statements or on anything
else discussed during this Conference?
DR. GARD: While I have been listening to the
reports and discussions this week, I have become
more and more convinced that the procedure we
are planning to follow in Sweden is both sound
and safe.
We have now used inactivated vaccine for four
years and the results obtained so far are very
good. We have not yet seen a single case of
paralytic poliomyelitis in about 2.5 million persons
who have received at least two doses of
our Swedish vaccine.
However, we do not know very much about the
duration of the protection that has been produced
and, whereas we feel fairly satisfied with the
findings in follow-up immunity studies, as far as
Types 2 and 3 are concerned, we should like to
reinforce Type 1 immunity. For this purpose,
we are planning to use a combined procedure,