Humoral immune response after SARS-CoV-2 vaccination in cladribine-treated multiple sclerosis patients

Multiple sclerosis immunomodulatory treatments such as cladribine, which affects both B- and T-lymphocytes, can potentially alter the humoral response to SARS-CoV-2 vaccination. This monocenter retrospective study reports on anti-SARS-CoV-2 IgG antibody response in cladribine treated MS patients and we compare the response in patients vaccinated before and after an 18-week interval after last cladribine dose. Of the 34 patients (5 patients ≤ 18 weeks and 29 patients > 18 weeks after last cladribine dose) that were included, 32 reached seropositivity (94 %). All patients vaccinated < 18 weeks after last cladribine dose reached seropositivity. This study confirms findings of earlier reports that cladribine-treated MS patients show an adequate humoral response after SARS-CoV-2 vaccination, even when vaccinated early (≤18 weeks) after last cladribine dose.