Safety and Immunogenicity Evaluation of the Recombinant Flagellin Protein Adjuvant

This study explored the dosing of the 3R-NC containing BA.2.86 strain, EG.5 strain, and WIV 1 strain receptor binding domain（RBD） with the the recombinant flagellin protein adjuvant KFD1 （KFD1）in healthy subjects, further evaluating the safety, tolerability, and immunogenicity of the recombinant flagellin protein adjuvant KFD1 （KFD1） as a mucosal immune enhancer. KFD1 was divided into four dosage groups (0μg, 20μg, 40μg, 80μg), with each dosage group receiving two administrations. Safety assessments were conducted 7 days after each dosage group, and the next dosage group could only be administered after confirming safety. Samples including saliva, nasal wash, and blood were collected at different time points after the two vaccinations to evaluate safety and immunogenicity.