The purpose of this study was to evaluated the effectiveness of inactivated poliovirus vaccine at a vaccine schedule that is commonly used in developing countries. The effectiveness of inactivated poliovaccine given at this schedule is important to national policy makers as they consider vaccination policies after the use of oral polio vaccine is discontinued.

After polio eradication, access to live polioviruses will be highly restricted, and oral poliovirus vaccine (OPV) use must be discontinued. OPV-using countries must decide whether to switch to inactivated poliovirus vaccine (IPV) or stop polio vaccination. Because only limited data are available on IPV immunogenicity in tropical developing countries, we conducted a randomized controlled trial of IPV in Cuba. The objectives of this study were to assess the humoral and mucosal immunogenicity conferred by IPV administered at the WHO-EPI schedule (6,10,14 wks of age) vs. placebo. A third arm was added to evaluate the immunogenicity of IPV administered at 2 and 4 months of age. Antibody titers were measured prior to the first dose as well as 1 month after the last dose in each study arm. Target sample size was 100 children in each arm. Mucosal (intestinal immunity) was measured indirectly through assessing poliovirus excretion in each group after a "natural challenge" of trivalent oral polio vaccine (OPV)recieved by study participants through their participation in the annual OPV mass campaigns approximately 1 month after their last dose of vaccine.

Inclusion Criteria:

Infants born 18 - 20 weeks prior to the first round of the 2002 National Immunization Days in cuba (in March 2002).

Born healthy at one of the 4 designated maternity hospitals in Cuba

Exclusion Criteria:

Serious congenital defect/disease at birth

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