COVID-19 vaccines in multiple sclerosis treated with cladribine or ocrelizumab.

Since the recent approval of vaccines against COVID-19, efficacy concerns emerged for MS patients treated with immunosuppressive drugs. We report our experience in four patients, under cladribine (two) or under ocrelizumab (two) treatment, all with low lymphocyte count, three of them vaccinated after 3 months from the last dose with good immune response, one (under ocrelizumab) after 2 months, without developing an appropriate title of antibodies. This experience suggests that the discriminant for the response to the vaccine is not the lymphocyte count but the timing of the vaccination.