Safety, tolerability and immunogenicity of Biological E’s CORBEVAX™ vaccine in children and adolescents: A Prospective, Randomised, Double-blind, Placebo controlled, Phase-2/3 Study

ABSTRACT Background After establishing safety and immunogenicity of Biological E’s CORBEVAX™ vaccine in adult population (18-80 years) in Phase 1-3 studies, vaccine is further tested in children and adolescents in this study. Methods This is a phase-2/3 prospective, randomised, double-blind, placebo controlled, study evaluating safety, reactogenicity, tolerability and immunogenicity of CORBEVAX™ vaccine in children and adolescents of either gender between <18 to ≥12 years of age in Phase-II and <18 to ≥5 years of age in Phase-III with placebo as a control. This study has two age sub groups; age subgroup-1 with subjects <18 to ≥12 years of age and age subgroup-2 with subjects <12 to ≥5 years of age. In both age sub groups eligible subjects (SARS-CoV-2 RT-PCR negative and seronegative at baseline) were randomized to receive either CORBEVAX™ vaccine or Placebo in 3: 1 ratio. Findings The safety profile of CORBEVAX™ vaccine in both pediatric cohorts was comparable to the placebo control group. Majority of reported adverse events (AEs) were mild in nature. No severe or serious AEs, medically attended AEs (MAAEs) or AEs of special interest (AESI) were reported during the study period and all the reported AEs resolved without any sequelae. In both pediatric age groups, CORBEVAX™ vaccinated subjects showed significant improvement in humoral immune-responses in terms of anti-RBD-IgG concentrations, anti-RBD-IgG1 titers, neutralizing antibody (nAb)-titers against Ancestral Wuhan and Delta strains. Significantly high interferon gamma immune response (cellular) was elicited by CORBEVAX™ vaccinated subjects with minimal effect on IL-4 cytokine secretion. Interpretations The safety profile of CORBEVAX™ vaccine in <18 to ≥5 years’ children and adolescents was found to be safe and tolerable. The adverse event profile was also found to be acceptable. Significant increase in anti-RBD IgG and nAb titers and IFN-gamma immune responses were observed post vaccination in both pediatric age sub groups. Both humoral and cellular immune responses were found to be non-inferior to the immune responses induced by CORBEVAX™ vaccine in adult population. This study shows that CORBEVAX™ vaccine is highly immunogenic and can be safely administered to pediatric population as young as 5 years old. The study was prospectively registered with clinical trial registry of India-CTRI/2021/10/037066