Immune response and protection from self-amplifying versus circular mRNA COVID-19 vaccines

Both SAM-RBD and Circ-RBD vaccines induced comparable anti-RBD IgG and virus-neutralizing antibody titers.

• Circ-RBD vaccines generated a higher memory T cell response compared to SAM-RBD vaccines.
• Circ-RBD vaccine remains stable for 4 weeks at 4°C.
• A bivalent Circ-RBD vaccine effectively neutralized both delta and omicron variants of SARS-CoV-2.
• Circ-RNA-RBD presents a promising candidate for COVID-19 vaccination.
• The findings support the potential of Circ-RNA vaccines for developing against rapidly emerging viral variants.

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