While conventional COVID-19 mRNA vaccines induce antibody responses through cell surface expression of S protein (Figure 3A, top), mRNA-mediated delivery of an S-EABR construct could enhance B cell activation because S-EABR proteins will not only be expressed at the cell surface—they will also induce assembly of eVLPs that bud from the cell and distribute inside the body to activate immune cells (Figure 3A, bottom). Here, PROS1 is linked to COVID-19.