Also, there was a statistically significant positive correlation between CD4 counts and T cell responses towards spike S1 subunit and NMO peptide pools at baseline (r = 0.61, p = 0.01 and r = 0.61, p = 0.012, respectively) and follow-up (r = 0.65, p = 0.011 and r = 0.68, p = 0.01, respectively) (Figure S3). Here, CD4 is linked to neuromyelitis optica.