LIVE POLIO IRUS VACCINES

8. PRELIMINARY REPORT ON THE SUSCEPTIBILITY OF
NEWBORN INFANTS TO INFECTION WITH POLIOVIRUS
STRAINS IN AN ATTENUATED VIRUS VACCINE
HENRY M. GELFAND, DOROTHY R. LEBLANC, ALFONSO H. HOLGUIN,
AND JOHN P. Fox*
DR. GELFAND (presenting the paper): A number
of studies have been reported during the past
several years wherein the efficacy of oral vaccination
of infants with attenuated poliovirus
vaccines was investigated.? - If practicable, the
practice of routine infant vaccination would
provide the easiest solution to the problem of
maintaining the immunity of a community against
poliomyelitis after safety and efficacy of a live
virus vaccine has been assured and it has been
received by the majority of the general population.
In previous studies, use was made of virus
strains developed by Dr. Hilary Koprowski and
by the Lederle Laboratories, administered in
monotypic or trivalent form, and under various
conditions of infant age, dose, and method of
evaluation. Nevertheless, it was generally
demonstrated that infection may be induced in
very young infants, even in the presence of high
titers of maternally-derived neutralizing antibody.
It had been suggested, however, that there
may be relative resistance to infection in the intestinal
tracts of very young infants, a resistance
which might be overcome by the administration
of larger doses than are required by older individuals.
The present investigation was undertaken to
extend these observations by a study of infant
susceptibility to infection with the "set" of attenuated
poliovirus strains developed by Dr. Albert
B. Sabin. By means of the administration of
graduated doses of each of the three types
separately, we hoped to perform infectivity titrations
in newborn infants in order to determine
the smallest effective doses which would result in
* Dr. Gelfand and Dr. Holguin (Communicable
Disease Center, U.S. Public Health Service, Department
of Health, Education, and Welfare, Atlanta,
Georgia); Miss LeBlanc (Division of Epidemiology,
Tulane University School of Medicine, New Orleans,
Louisiana); and Dr. Fox (Division of Epidemiology,
Public Health Research Institute, New York, N. Y.).
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virus excretion and subsequent antibody response
in a satisfactory proportion of babies of an age
which would be suitable for routine use. In addition,
the course of infection following trivalent
vaccination was to be examined in detail, and certain
other variables of age and inoculation regime
were to be investigated.
MATERIALS AND METHODS
Study group. The original plan called for the
recruitment of 230 mothers and their two- to
three-day-old infants at the time of discharge
from the maternity ward of a hospital in New
Orleans, and 45 mothers and their 30-day-old
babies at the time of the first post-partum visit.
Only lower-economic-group Negro mothers and
babies who were in good health following an uncomplicated
pregnancy and delivery were selected.
The program was fully explained and
written agreement to participate was obtained
from the mothers by the nurse-epidemiologist
(D.R.L.).
The entire group of babies was divided into
the subgroups shown in Table 1. Groups 1, 2,
and 3 act as the basic titration of each of the
vaccine types separately, and group 5 serves to
compare older infants with the younger with
reference to Type 1 vaccine virus. Group 4 was
established to determine whether multiple feeding
of the same virus type on three successive
days and in maximum concentration would increase
the likelihood of infection. Group 6 consists
of babies who received trivalent vaccine
either once or on three successive days. Group
7 received no vaccine, and serves as an illness
and "wild virus" infection control. Since groups
1-5 were fed only one virus type, they also serve
as built-in "wild virus" infection controls for the
types not being fed.
Only babies of group 6 were selected on the
basis of birth order. Since these infants received