A Study to Evaluate Immunogenicity of Intramuscular Full-Dose and Intradermal Fractional Dose of IPV

The study will assess and compare the immune response to full-dose inactivated polio vaccines (IPV) via intramuscular (IM) administration and of the fractional dose of inactivated poliovirus vaccine (f-IPV) via intradermal (ID) administration, in different schedule combinations in the Expanded Program on Immunization (EPI) primary series.

This study prioritizes comparisons involving two-dose regimens recently recommended by the World Health Organization (WHO) Strategic Advisory Group of Experts on immunization (SAGE) and Pan American Health Organization (PAHO) in response to global IPV supply shortages 21. Furthermore, the study will provide data on the comparative humoral immunogenicity of various schedules to inform polio immunization policy for the post-eradication era. The study population will include infants in Dominican Republic and Panama. Absence of wild and circulating vaccine derived polioviruses along with the lack of regular Supplementary Immunization Activities (SIAs) in the Latin America region provide an ideal epidemiologic setting to study polio vaccine immunogenicity. Infants will receive two or three doses of full-dose IPV IM or f-IPV ID, in two schedules (10, 14 and 36 weeks and 14 and 36 weeks). Immunological and safety assessments will be made after one dose, two doses and three doses. A total of 773 infants will be enrolled and distributed into 4 groups, according to a randomization scheme. During the study period, infants will be administered other concomitant vaccines according to the national schedules of the participating countries, but the effect, if any, of the concomitant administration on IPV immunogenicity will not be assessed. Optimum immunogenicity expected from the dose(s) of IPV in the post-eradication era will have to be balanced with the cost and supply constraints of IPV. This study will be critical to determine how many doses of IPV and which schedule are optimal for the post-eradication era after the global cessation of Oral Polio Vaccine (OPV) use.