Describe the mRNA vaccines that help protect against SARS-CoV-2 (Covid-19). Briefly describe the antigen that results from this vaccination. What specific non-self shape is produced that stimulates an immune response? Is it a portion of the sequence of the Covid-19 genome, a portion of the Covid-19 lipid bilayer, the entire Covid-19 lipid bilayer, a portion of the Covid-19 spike protein, or the entire Covid-19 spike protein?