This is a speed-up that pre-dates the mRNA trick Moderna had been working on, a virus from chimps (so humans aren't immune to it because it wouldn't infect humans normally, yet chimps are similar enough that the virus can get into a human cell) but hollowed out to make whatever you want instead of more copies of itself. You put any payload inside it and it'll re-program the patient's cells to make that for a brief period until the immune system cleans up the mess. This vaccine uses the spike protein as payload to train your immune system.