Quantification of SARS-CoV-2-specific neutralizing antibody titer in U/ml after booster vaccination during ofatumumab treatment. All patients with available data were included in the analysis, and individual values are represented by dots. Dotted line indicates assay-specific cutoff for seropositivity. The color scheme indicates initial neutralizing antibody titers (yellow: seronegative patients at the time of the first booster; blue: seropositive patients with moderate level of neutralizing antibody titers at the time of the first booster; black: seropositive patients with high level of neutralizing antibody titers at the time of the first booster; gray: no baseline level of neutralizing antibodies available). Time of COVID-19 infections and timing of additional boosters are indicated in the individual courses. An integrated table gives an overview of key parameters per case (sorted by the level of neutralizing antibody titers at month 12): seropositivity at the time of vaccination (+), additional booster vaccination received during the study (+), COVID-19 infection reported during the study (+), strength of increase in neutralizing antibody titers after first booster compared to baseline (<2-fold; >2-fold, >4-fold, and >10-fold); DMT received during initial vaccination (yes = continued DMT/no = DMT interrupted/naïve = no DMT prior and during vaccination). *no neutralizing antibody titer available at month 12 due to technical issues; **no baseline value; ***rounded. DMT: disease-modifying therapy; n.a.: not available; nAB: neutralizing antibody.