LIVE POLIO IRUS VACCINES

394 Efficacy-Laboratory Evidence
TABLE 9. SUMMARY OF TESTS OF ANTIBODY RESPONSE OF CHILDREN WITH No DETECTABLE ANTI-
BODY FOR THE RESPECTIVE TYPE OF POLIOVIRUS PRIOR TO VACCINATION IN THREE OF THE CITIES IN
WHICH SABIN'S ORAL VACCINE WAS USED
Serologic response
Cit7y
T___'_pe 1 Type 2 Type 3
Number umber and Number Number and Number Number and
tested percent positive tested percent positive tested peroent positive
Mexico City 61 54 46 40 64 51
88% 87% 80%
GuadalaJara 9 8 6 5 8 7
89% 83% 87%
Monterrey 29 21 39 29 27 14
72% 74% 52%
A11 99 83 91 74 99 72
84% 81% 73%
The immunogenic activity of the vaccine is
shown in Table 9, which shows the antibody conversion
rate in a randomly selected group of
children from three of the cities under study.
These data are based on simultaneous tests using
the cytopathogenic effect method in roller-tube
cultures of human kidney cells on paired sera
collected before feeding Type 1 and three to four
weeks after feeding Type 2.
The conversion rate for all three types was very
similar in Mexico City and in the City of Guadalajara,
although the number of children tested
in the latter is very small. Thus, for Type 1 the
conversion rate was 88 per cent and 89 per cent,
for Type 2, 87 per cent and 83 per cent, and for
Type 3, 80 per cent and 87 per cent respectively.
In the City of Monterrey, the antibody conversion
rate was lower; for Type 1, 72 per cent, for Type
2, 74 per cent, and for Type 3, 52 per cent. The
over-all response in the three cities was 84 per
cent for Type 1, 81 per cent for Type 2, and
73 per cent for Type 3. The actual titers observed
after vaccination are shown in Table 10. Although
the antibody rise is somewhat variable
with the individual, it can be noted that among
those who responded, the majority of them (72
per cent for Type 1, 53 per cent for Type 2, and
74 per cent for Type 3) slhowed titers of 1:100 or
more.
The relationship of age to development of antibodies
after feeding of the vaccine is shown in
Table 11. It is clearly evident that antibody response
increases with age. This observation probably
could be explained on the basis of the interference
upon the vaccine strains of a great variety
of non-polio enteroviruses, which are known to be
present in a high percentage of children under
one year of age in Mexico.
During the course of the vaccination program,
some minor complaints, such as diarrhea, and
occasionally vomiting and fever, were reported in
some of the vaccinated children; however, these
minor symptoms were not more frequent than
would normally be expected in a population that
is known to be highly infected with all kinds of
enteropathogens.
The number of paralytic cases reported in
the vaccinated areas is presented in the following
five tables. Table 12 shows the data for the
City of Monterrey, in which 52.3 per cent of the
estimated population of children under five years
of age were fed the vaccine. This city had experienced
epidemics in the last two years and an
outbreak was expected in 1959. Only 14 cases
of paralytic poliomyelitis were reported throughout
the year and all of them among non-vaccinated
children. The data for the City of Puebla
are presented in Table 13. In this city, about