What's to keep this from happening? Why didn't they include more antigens in the vaccines to generate a more holistic immune response (pic related)? I get that the S1 component is genetically stable enough in computer models to preclude sizable genetic drift in the near future since it's vital to the spike protein's 3D structure, but there are other coronaviruses in the wild and if you're vaccinating against only one component of an antigen you're exerting extreme selective pressure on the virus for that region to undergo mutation somehow. Why not include some nucleocapsid mRNA in there or something?