LIVE POLIO IRUS VACCINES

Live Poliovirus Immunization-Conditions of Infection with Other Viruses 381
TABLE 2. SELF-LIMITED CHARACTER OF DISSEMINATION OF POLIOVIRUSES AFTER RAPID MASS ORAL
ADMINISTRATION OF TRIVALENT VACCINE IN A TROPICAL COMMUNITY
Carrier Rate of Polioviruses and Other Enteric Viruses Among 1 to 5-Year-Old Children Selected at
Random Before and 3 Months After Single Dose (105.2-105.6 TCDjo) of Trivalent Oral Poliovirus Vaccine
(Sabin) Fed Within Few Days to 86 Per Cent of Children (Newborn to 10 Years) in Toluca, Mexico.
Total No. Tested
Incidence of Polioviruses (P)
Incidence of Other Enteric Viruses (NP)
Ratio NP/P
BEFORE VACCINE
AUG. 1959
719
11.0%
50.8%
4.6
THREE MONTHS
AFTER VACCINE
417
0.7%
50.6%
72.3
Carrier Rate Based on Detection of Virus in Single Rectal Swabbing-Actual
Higher
Carrier Rate is Somewhat
end of three months reached a point that was
markedly lower than before the mass feeding of
the live poliovirus vaccine.
The self-limited character of dissemination of
polioviruses after this rapid mass feeding of
live poliovirus vaccine, under conditions which
favor the continued extensive dissemination of
enteric agents, is strikingly brought out in Table
2, which shows the results of tests on 1,135
randomly selected one to five-year-old children.
The isolation rate of non-poliomyelitis enteric
viruses was about 51 per cent before and also
three months after the vaccination program, while
the isolation of polioviruses dropped from 11 per
cent to 0.7 per cent-a 16-fold diminution.
The serologic effect of this temporary dominance
of the polioviruses is shown in Table 3,
in which the antibody conversion rates during
the first 10 weeks after the mass feeding of a
single dose of trivalent vaccine in Toluca is compared
with the natural antibody conversion rates
in the city of Querétaro, which is similar in
TABLE 3. DEVELOPMENT OF POLIO NEUTRALIZING ANTIBODIES DURING COMPARABLE 10-WEEK
PERIOD IN TWO MEXICAN CITIES
(a) Toluca-After one dose of trivalent vaccine (0.01 ml. of each-10 '5 2 to 105.6 TCD,,).
(b) Querétaro-No oral vaccine.
Conversion rates for indicated type based on simultaneous tests on paired sera from originally
negative children.
TOLUCA-VACCINE
QUERITARO-No VACCINE
TYPE
No.*
1 36/53 68 2/33 6
2 64/77 82 3/33 10
3 33/76 43 5/38 13
*Children without antibody who were carriers of poliovirus at time first blood specimen was obtained
are excluded from this calculation.
No.
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