In preclinical studies, COVID-19 vaccine demonstrated positive immunogenic profile. All of the animals (100%) were seroconverted by day 19 at a single dose of 2µg. Moreover, it also showed that the self-transcribing and replicating (STARR™) mRNA induced higher seroconversion relative to conventional mRNA at equivalent doses. In contrast, anti-SARS-CoV-2 IgG and IgM antibody titers were also higher. At day 30 post vaccination, 80% of mice vaccinated with 0.2 µg COVID-19 vaccine elicited antibodies that neutralised 50% of SARS-CoV-2 virus at titers 20 and above. The geometric mean titer of the 4 animals with titers >20 was 57.72 (SD = 2.032). At the same time point, 100% of animals vaccinated with 2µg of COVID-19 vaccine developed antibody titers >20, with geometric mean titer of 217.9 (SD = 1.365). However, 80% of animals vaccinated with 10µg of COVID-19 vaccine developed antibody titers of 320 or greater, which was the upper limit of dilution of this test   .
In preclinical studies, COVID-19 vaccine showed a robust and balanced immune response. The dose dependent CD8+ T-cell response, with a clear response observed at all doses, as well as a balanced Th1/Th2 CD4+ T-cell immune response. The percent of CD8+ T-cells increased from the 4% baseline to 8% with increasing doses of STARR™ mRNA. The Th1/Th2 ratio for T-helper cells (CD4+) showed a strong TH1 response which does not change with increasing dose, indicated that the immune response remains balanced across all dose levels  .