The primary objectives of the study are:
To describe the neutralizing antibody profile at Day 1, Day 22, and Day 36 of each study intervention group.
To describe the safety profile of all participants in each age group and each study intervention group up to 12 months post-last injection.
The secondary objectives of the study are:
To describe binding antibody profile at Day 1, Day 22, Day 36, Day 181 (Cohort 1) or Day 202 (Cohort 2), and Day 366 (Cohort 1) or Day 387 (Cohort 2) of each study intervention group.
To describe the neutralizing antibody profile at Day 181 (Cohort 1) or Day 202 (Cohort 2) and at Day 366 (Cohort 1) and Day 387 (Cohort 2) of each study intervention group.
To describe the occurrence of virologically-confirmed COVID-19-like illness and serologically-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
To evaluate the correlation/association between antibody responses to SARS-CoV-2 Recombinant Protein and the risk of COVID-19-like illness and/or serologically-confirmed SARS-CoV-2 infection.
The interim Phase 1/2 results showed a level of neutralizing antibody titers after two doses comparable to sera from patients who recovered from COVID-19, balanced cellular response in adults aged 18 to 49 years, but insufficient neutralizing antibody titers in adults over the age of 50.
The candidate showed transient but higher than expected levels of reactogenicity due to the suboptimal antigen formulation, with no serious adverse events related to the vaccine candidate.
The most favorable results were observed in the group which tested the highest antigen concentration, combined with the GSK adjuvant, showing neutralization titers in 88% of participants.
Seroconversion was observed in 89.6% of the 18 to 49 age group, 85% in the >50 age group, and 62.5% in the >60 age group.