CD8A and Miyoshi myopathy: Similar to the observation of reduced frequencies of SARS-CoV-2-specific CD8+ T cells in convalescent MM patients, three mRNA vaccine doses also induced significantly lower frequencies of spike-specific CD8+ T cells against the T cell epitope A*02/S269-277 in MM patients compared to HCs (4.520 × 10−5 vs. 4.450 × 10−4, p = 0.0025) (Figure 3A).