LIVE POLIO IRUS VACCINES

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14. EFFECTS OF RAPID MASS IMMUNIZATION OF A POPULATION
WITH LIVE, ORAL POLIOVIRUS VACCINE UNDER CONDITIONS
OF MASSIVE ENTERIC INFECTION WITH OTHER VIRUSES*
ALBERT B. SABIN
AND
M. RAMOS ALVAREZ, J. ALVAREZ AMÉZQUITA, W. PELON, R. H. MICHAELS,
I. SPIGLAND, M. KOCH, J. BARNES, AND J. RHIM
The Children's Hospital Research Foundation, University of Cincinnati College of
Medicine, Cincinnati, Ohio; The Children's Hospital, Mexico City, Mexico; and the
Ministry of Public Health and Welfare of Mexico
DR. SABIN (presenting the paper): In the
absence of enteric infection with other viruses,
the feeding of a single type of live poliovirus
vaccine to children, who had not previously
been infected with the same type of poliovirus,
usually results in viral multiplication in the
intestinal tract, antibody formation, and complete
or partial resistance to reinfection. The use of
live poliovirus vaccine in areas with climatic and
hygienic conditions which permit extensive dissemination
of naturally occurring polioviruses
and other enteric viruses throughout the year
has been complicated by the problem of viral
interference,`l 2 which we have attempted to overcome
by the tactics to be described in this communication.
The studies of Ramos Alvarez and
his associates 3 in Mexico and of Plotkin and
Koprowski 4 in the Belgian Congo, have shown
that vaccination programs in large cities that are
spread out over a period of many weeks and
include only a small fraction of the susceptible
population, not only fail to immunize a considerable
proportion of the vaccinated children but
also have little or no influence on the dissemination
of the ever-present, naturally occurring
paralytogenic strains of poliovirus. Accordingly,
it seemed necessary to determine whether or not
at least temporary dominance over the naturally
occurring polioviruses and other interfering
enteric viruses could be achieved by feeding a
mixture of all three types of poliovirus vaccine
to almost all susceptible children within a period
* This study was aided by a grant from The National
Foundation.
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of a few days. The reason for using a trivalent
mixture instead of feeding the three types
separately at intervals of four to six weeks, which
I regard as optimum during the cold months of
the year in temperate zones, was to implant all
three types of the vaccine strains in the largest
number of children, and then let nature help
in their further dissemination in the community.
This study was carried out in Toluca, Mexico,
in August 1959. Dr. Ramos Alvarez and his
associates in Mexico were responsible for the
field work and the collection of specimens, and
all the virologic and serologic work was carried
out in Cincinnati. Toluca, located at about 19 °
N. latitude, has a total population of about
100,000. A serologic survey of the population
just before initiation of the vaccine program indicated
that 90 to 100 per cent of the children become
immune to all three types of poliovirus
during the first four years of life (Fig. 1).
According to available data for the past five
years, this city has been paying an average price
of 14 paralytic cases per year for this naturally
acquired immunity. Twenty cases of paralytic
poliomyelitis had already been reported in 1959,
when our study began during the second week
of August. Rectal swabbings from 1,892 persons
-newborn to 10 years of age and mothers-obtained
at random in different parts of the city
within a few days before the vaccination program,
were each tested in monkey kidney and human
epithelioma (Hep.-2) tissue cultures, as well as
in newborn mice. The results, summarized in
Fig. 2, indicate that the special methods used
revealed a much higher incidence of natural