LIVE POLIO IRUS VACCINES

13. MINNESOTA STUDIES WITH ORAL POLIOMYELITIS VACCINE.
COMMUNITY SPREAD OF ORALLY ADMINISTERED
ATTENUATED POLIOVIRUS VACCINE STRAINS*
ANNE C. KIMBALL, PH.D., ROBERT N. BARR, M.D., HENRY BAUER, PH. D.,
HERMAN KLEINMAN, M.D., EUGENE A. JOHNSON, PHD., AND
MARION COONEY, M.S.t
DR. KIMBALL (presenting the paper): In the
1958 Minnesota study of orally administered attenuated
poliovirus vaccine' the feeding of virus
to only half of the participating families during
the control period provided an opportunity to
study the spread of these strains of poliovirus
within the community to the participants who received
placebos. Prior to this study, intrafamily
2' "' and intra-institutional' spread of attenuated
polio vaccine viruses had been reported.
This study presents quantitative data in regard to
the community spread of vaccine strains of poliovirus.
The poliovirus vaccine strains used in this study
were developed by Cox. No harmful effects were
attributed to the use of these strains in the 1958
Minnesota study nor in later studies conducted
in Minnesota, Latin America and elsewhere.
Natural human passage might be expected to
produce changes in any property of these vaccine
strains and intensive study of these passage
strains is indicated. One crucial test for change
is available from the medical history of the individuals
receiving these strains by natural spread;
a review of the detailed medical records of these
individuals is presented. If after several natural
passages in humans the strains do not show a
persistent and progressive increase in virulence,
the spread of these vaccine strains could have
definite value; not only would some immunity be
acquired by individuals not fed the vaccine
strains but also the intermittent presence of these
* This is one of a series of papers. Aided by grants
from the Sister Elizabeth Kenny Foundation, Minneapolis,
Minnesota and Lederle Laboratories, Division
of the American Cyanamid Company, Pearl
River, New York.
t Dr. Kimball, Dr. Barr, Dr. Bauer, Dr. Kleinman
and Miss Cooney (Minnesota Department of Health);
Dr. Johnson (School of Public Health, University of
Minnesota).
strains in a community could provide booster
stimulation to previously vaccinated individuals.
The magnitude of interfamily or community
spread of these strains can indicate the extent of
added benefit that can be anticipated.
MATERIALS AND METHODS
Participants were married University of Minnesota
students and their children who lived in e
crowded university housing development in Minneapolis,
known as Como Village.
Design of the study, the vaccine strains used
and the characteristics of the study population
have been described.' All village residents (371
families) were invited to participate, and 149
fainilies (40 per cent) volunteered. Thus members
of 20 per cent of the households were fed
vaccine (group B) and specimens were available
from an additional 20 per cent of the households
for the measure of community spread of the vaccine
strains. The division of the participants into
group A (74 families) and group B (75 families)
was on a random basis. During the study period
the identity of these groups was known only to
one member of the team (E.A.J.) who made the
random division and distributed the vaccine and
placebo capsules into envelopes labeled for each
family. The identity of the blood serum and
stool specimens were not known to the laboratory
personnel at the time of testing.
Three stool specimens were available from the
control group (A) for isolation of each of the
three respective poliovirus types. As can be observed
in Table 1, showing the chronology and
sequence of the feeding and collection of specimens,
each participant submitted a total of six
stool specimens. The first stool specimens
were collected prior to the feeding of vaccine to
either group. The second, third, and fourth
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