Background
multiple sclerosis, RRMS
VIRUS, MULTIPLE SCLEROSIS
Natalizumab (NTZ) and ocrelizumab (OCR) can be used for the treatment of relapsing–remitting multiple sclerosis (RRMS). In patients treated with NTZ, screening for JC virus (JCV) is mandatory, and a positive serology usually requires a change in treatment after 2 years. In this study, JCV serology was used as a natural experiment to pseudo-randomize patients into NTZ continuation or OCR.