Phase I: To assess the composite endpoints of vaccine safety and reactogenicity of RBD SARS-CoV-2 HBsAg VLP vaccine containing different adjuvant combinations as compared with placebo in healthy adults aged 18 - 45 years as determined through participant reported (solicited and unsolicited) and clinically identified local and systemic adverse events (e.g. blood tests; vital signs; physical examination).[Participant reported events recorded daily for 7 days post-vaccination and then on occurrence up to 180 days post-vaccination];Phase II; To assess the immune response of two dose strengths and two adjuvant types contained within RBD SARS-CoV-2 HBsAg VLP vaccine as compared with placebo in healthy adults aged 18 - 79 years as determined through assessment of antibody titre and cellular immunity 56 days from first dose. Immune response will be measured through analysis of blood samples.[Increase in neutralising antibody titres and anti-SARS-CoV-2 IgG antibodies as measured at Days 0; 28 and 56 from first vaccine administration];Phase II; To assess the composite endpoints of safety and reactogenicity of RBD SARS-CoV-2 HBsAg VLP vaccine administration as compared with placebo in healthy adults aged 18 - 79 years as determined through participant reported and clinically identified local and systemic adverse events. This will include safety blood assessment and the recording of solicited and unsolicited local and systemic adverse events by participants via an electronic diary or by the clinical staff as part of scheduled clinic visits[Participant reported events reported daily for 7 days post-vaccination and then on occurrence up to 180 days post-vaccination]

Phase I: To assess the composite endpoints of vaccine safety and reactogenicity of RBD SARS-CoV-2 HBsAg VLP vaccine containing different adjuvant combinations as compared with placebo in healthy adults aged 18 - 45 years as determined through participant reported (solicited and unsolicited) and clinically identified local and systemic adverse events (e.g. blood tests; vital signs; physical examination).[Participant reported events recorded daily for 7 days post-vaccination and then on occurrence up to 180 days post-vaccination];Phase II; To assess the immune response of two dose strengths and two adjuvant types contained within RBD SARS-CoV-2 HBsAg VLP vaccine as compared with placebo in healthy adults aged 18 - 79 years as determined through assessment of antibody titre and cellular immunity 56 days from first dose. Immune response will be measured through analysis of blood samples.[Increase in neutralising antibody titres and anti-SARS-CoV-2 IgG antibodies as measured at Days 0; 28 and 56 from first vaccine administration];Phase II; To assess the composite endpoints of safety and reactogenicity of RBD SARS-CoV-2 HBsAg VLP vaccine administration as compared with placebo in healthy adults aged 18 - 79 years as determined through participant reported and clinically identified local and systemic adverse events. This will include safety blood assessment and the recording of solicited and unsolicited local and systemic adverse events by participants via an electronic diary or by the clinical staff as part of scheduled clinic visits[Participant reported events reported daily for 7 days post-vaccination and then on occurrence up to 180 days post-vaccination]