CD40LG and myeloid sarcoma: The prevalence of SARS-CoV-2 IgG/IgM in MS patients (n = 9, 2.9%) was significantly lower than in the high-risk population (n = 25, 10.6%) (p < 0.001), and similar to the low-risk population (n = 11, 1.3%) (p = 0.057); these results were also confirmed after random matching by age and sex (1:1:1).