Interim Report of a Phase 2 Randomized Trial of a Plant-Produced Virus-Like Particle Vaccine for Covid-19 in Healthy Adults Aged 18-64 and Older Adults Aged 65 and Older

The rapid spread of SARS-CoV-2 globally continues to impact humanity on a global scale with rising morbidity and mortality. Despite the development of multiple effective vaccines, new vaccines continue to be required to supply ongoing demand. We report Day 42 interim safety and immunogenicity data from a Phase 2, randomized, placebo-controlled trial in Adults aged 18+ immunized with a virus-like particle vaccine candidate produced in plants displaying SARS-CoV-2 spike glycoprotein (CoVLP) adjuvanted with AS03 (NCT04636697). This report focuses on presenting safety, tolerability and immunogenicity, as measured by neutralizing antibody (NAb) and cell mediated immunity (IFN-{gamma} and IL-4 ELISpot) responses, in Adults aged 18-64 (Adults) and Older Adults aged 65+ (Older Adults). CoVLP adjuvanted with AS03 was well-tolerated and adverse events (AE) were primarily mild or moderate and of transient duration. AEs in Older Adults were more limited than those observed in the Adult population. CoVLP with AS03 induced a significant humoral immune response in both age cohorts. CoVLP with AS03 induced a greater humoral response in Adults than Older Adults after a single dose but this effect was overcome with a second dose when both age cohorts responded with NAb titers that were [~]10-fold higher than those in a panel of sera from patients recovering from COVID-19. A single dose of CoVLP with AS03 induced a significant IFN-{gamma} response in both age cohorts; a second dose significantly boosted IFN-{gamma} and IL-4 responses in both age cohorts. Adults generated a stronger IFN-{gamma} and IL-4 cellular response than did Older Adults after one or two doses of AS03-adjuvanted CoVLP. Safety and immunogenicity from Adults with comorbidities as well as final safety and immunogenicity responses after 12 months will be reported upon availability.