Study of Inactivated Poliovirus Vaccine Given at an Earlier Schedule With Shorter Intervals

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.