Phase 3 Trial Of A Sabin Strain-Based Inactivated Poliovirus Vaccine

Background. The development of a Sabin strain-based inactivated poliovirus vaccine (Sabin-IPV) is imperative to protecting against vaccine-associated paralytic poliomyelitis in developing countries.Methods. In this double-blinded, parallel-group, noninferiority trial, eligible infants aged 60-90 days were randomly assigned in a ratio of 1: 1 to receive either 3 doses of Sabin-IPV or Salk strain-based IPV (Salk-IPV) at 30-day intervals and a booster at the age of 18 months. Immunogenicity and safety were assessed on the basis of a protocol.Results. Of 1438 infants, 1200 eligible infants were recruited and received either Sabin-IPV or Salk-IPV. From the Sabin-IPV and Salk-IPV groups, 570 and 564 infants, respectively, completed the primary immunization and formed the per-protocol population. The seroconversion rates of the participants who received Sabin-IPV were 100%, 94.9%, and 99.0% (types I, II, and III, respectively), and those of the participants who received Salk-IPV were 94.7%, 91.3%, and 97.9% 1 month after the completion of primary immunization. An anamnestic response for poliovirus types I, II, and III was elicited by a booster in both groups. Except in the case of fever, other adverse events were similar between the 2 groups.Conclusions. The immune response induced by Sabin-IPV was not inferior to that established with Salk-IPV.