CD4 and infection: Notably, T pwMS in which occurred a natural COVID-19 infection after vaccination display a higher frequency of both CD4 (0.24% ± 0.15; p=0.016) and CD8+(0.19% ± 0.18; p= 0.04) S-specific T cells response compared to T pwMS who remains protected from the infection (0.09% ± 0.03 and 0.05% ± 0.02 respectively, Figures 5B, D).