A Study on the Safety, Tolerability and Immune Response of SARS-CoV-2 Sclamp (COVID-19) Vaccine in Healthy Adults

This study will be conducted in 2 parts: Part 1 will include a young healthy adult population aged ≥ 18 - ≤ 55 years and Part 2 will include an older healthy adult population aged 56 years and over. The study will consist of 6 cohorts: 2 cohorts of a lower dose (Treatment A), 2 cohorts of an intermediate dose (Treatment B) and 1 cohort of a higher dose (Treatment C) (Part 2 only), and 1 cohort of a higher dose examining both a two dose regimen (Treatment C) and a single dose vaccination regimen (Treatment D) (Part 1 only). Cohorts 1,2 and 3 will include subjects aged ≥ 18 - ≤ 55 years of age and cohorts 4, 5 and 6 will include subjects aged 56 years and older. Cohorts 4, 5 and 6 will include an approximately equal number of subjects aged ≥ 56 - ≤ 65 years of age, and ≥ 66 years and over. Part 1: Cohort 1 will include 32 subjects; of these 8 will receive placebo, and 24 subjects will receive Treatment A. Cohort 2 will include 32 subjects; of these 8 will receive placebo, and 24 subjects will receive Treatment B. Cohort 3 will include 56 subjects; of these 8 will receive placebo, 24 subjects will receive Treatment C, and 24 subjects will receive Treatment D. Part 2: Cohort 4 will include 32 subjects; of these 8 will receive placebo, and 24 subjects will receive Treatment A. Cohort 5 will include 32 subjects; of these 8 will receive placebo, and 24 subjects will receive Treatment B. Cohort 6 will include 32 subjects; of these 8 will receive placebo, and 24 subjects will receive Treatment C. Sentinels will be used for each cohort in Part 1 such that the first two subjects will receive either the first dose of SARS-CoV-2 Sclamp vaccine or placebo. After at least 24 hours from the time of administration of the first doses a review of the immediate post-vaccination safety data will be conducted by the Safety Review Committee (SRC) in accordance with the study protocol. Should there be no safety concerns, the remaining participants in each cohort will be dosed. The step-wise dose escalation study design is an additional precautionary measure, where the lower dose cohort will complete their first vaccination, and the cumulative safety data from the first 7 days will be evaluated by the SRC prior to initiating vaccination with the next higher dose of vaccine. Cohorts will be dosed sequentially, and escalation from Cohort 1 to Cohort 3 will be authorised by the SRC if no safety events of concern are observed in subjects up to Day 8 following review of the cumulative safety data of each Cohort. After the first vaccination dose has been administered to Cohorts 1, 2 and 3 and the aggregated safety data reviewed by the SRC, vaccination will be initiated for Cohorts 4, 5 and 6. These Cohorts will not include sentinels, however, the SRC will review the aggregated/cumulative safety and tolerability data up to at least Day 8 post vaccination for all subjects in each of Cohorts 4, 5 and 6 by cohort before proceeding to the second vaccination dose. Subjects will receive two single intramuscular (IM) doses of the following study treatments at 28 days apart as follows: IM administration (to the deltoid region of the subjects non dominant arm, administered by a registered nurse \[RN\]) of SARS-CoV-2 Sclamp adjuvanted vaccine, administered on Days 1 and 29, of one of the following treatments: Treatment A (Cohorts 1 \& 4): SARS-CoV-2 Sclamp vaccine 1 x 5 mcg in 0.5 mL suspension, administered as two separate doses at least 28 days apart Treatment B (Cohorts 2 \& 5): SARS-CoV-2 Sclamp vaccine 1 x 15 mcg in 0.5 mL suspension, administered as two separate doses , at least 28 days apart Treatment C (Cohorts 3 \& 6): SARS-CoV-2 Sclamp vaccine 1 x 45 mcg in 0.5 mL suspension, administered as two separate doses at least 28 days apart Treatment D (Cohort 3 only): SARS-CoV-2 Sclamp vaccine 1 x 45 mcg in 0.5 mL suspension, followed by placebo administered as the second dose at least 28 days apart. The proposed escalation scheme for the study consists of two three-fold dose increments. The planned dose range of 5 mcg to 15 mcg to 45 mcg administered 28 days apart was selected to minimize the risk to the subjects while ensuring the evaluation of an exposure range that encompasses and exceeds the expected level to achieve an immunological response. The SRC will be responsible for the assessment of available safety and tolerability data for each cohort and to make decisions with regards to study progression. The study will be unblinded prior to Day 394. All subjects that received an investigational vaccine product (not placebo) will be offered to return for optional annual follow-up visits beyond Day 394 to determine the duration of the HIV diagnostic cross-reactivity. Samples from this visit will be tested for cross-reaction in HIV point of care and rapid diagnostic tests.