The IPX-822 vaccine works by introducing the VSV vector into the body, where it infects cells and expresses the SARS-CoV-2 spike protein. This leads to the activation of immune cells, including dendritic cells, T-cells, and B-cells, which recognize the spike protein as foreign and mount an immune response. The immune response generates neutralizing antibodies and cell-mediated immunity, providing protection against SARS-CoV-2 infection.