CD4 and COVID-19: Here we find that a T cell vaccine (“MIT-T-COVID”) that contains the human HLA-A*02:01 displayed subset of our COVID-19 T cell vaccine and additional mouse specific CD4+ epitopes provides effective prophylaxis against the onset of SARS-CoV-2-induced morbidity and mortality caused by SARS-CoV-2 Beta infection in transgenic mice carrying HLA-A*02:01.