Safety, Immunogenicity, and Lot-to-lot Consistency of a Multidose Sabin Strain-Based Inactivated Polio Vaccine: a Phase III, Randomized, Blinded, Positive-Control Clinical Trial in Infants Aged 2 Months.

Objectives: To evaluate the safety, immunogenicity, and lot-to-lot consistency of Sabin strain-based inactivated polio vaccine (sIPV) in a five-dose vial presentation.Methods: Stage I was an open-label safety observation, in which 72 healthy subjects (including 24 adults, children, and infants each) were given one or three doses of the five-dose vial sIPV; stage II was a randomized, blinded, and positive-control study, in which 1500 infants were randomized at the ratio of 1: 1: 1: 1: 1 into five groups to receive either three doses of the five-dose sIPV three lots, a conventional inactivated poliovirus vaccine, or a single-dose sIPV as controls, for primary immunization. Safety, immunogenicity, and lot-to-lot consistency were assessed.Results: Among 1456 subjects who completed the primary immunization, the geometric mean titer ratios of types 1, 2, and 3 of each pair of lots were all within the equivalence criteria margin (0.67-1.50). The seroconversion rates of types 1, 2, and 3 in the combined test group were 98.02%, 94.07%, and 98.77%, respectively, which were noninferior to both control groups. The overall incidence of adverse reactions was 29.68% and erythema was the most common adverse reaction with incidences of 10.47%,9.33%, and 9.73% in the combined test group and control groups ( P > 0.05).Conclusion: The five-dose sIPV demonstrated good safety, immunogenicity, and lot-to-lot consistency.(C) 2023 Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )