1,2Bassem I Yamout, 3Peter Rieckmann, 4Diego Centonze, 5Gavin Giovannoni, 6Le H. Hua, 7,8Celia Oreja-Guevara, 9Daniel Selchen, 10Per Soelberg Sørensen, 11Patrick Vermersch, 12Heinz Wiendl, 13Hashem Salloukh

1Nehme and Therese Tohme Multiple Sclerosis Center, American University of Beirut, Beirut, Lebanon; 2Neurology Institute, Harley Street Medical Center, Abu Dhabi, UAE; 3Center for Clinical Neuroplasticity, Medical Park Loipl, Bischofswiesen, Department of Neurology, University of Erlangen, Germany; 4Unit of Neurology and Neurorehabilitation, IRCCS Neuromed, Pozzilli (IS), Italy; 5Queen Mary University of London, Blizard Institute, Barts and The London School of Medicine and Dentistry, London, UK; 6Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA; 7Neurology, Hospital Clínico San Carlos, Idissc, Madrid, Spain; 8Departamento de Medicina, Facultad de Medicina, Universidad Complutense de Madrid, Spain; 9University of Toronto, Division of Neurology, St. Michael’s Hospital, Toronto, ON, Canada; 10Danish Multiple Sclerosis Center, Department of Neurology, University of Copenhagen and Rigshospitalet, Copenhagen, Denmark; 11Université de Lille, INSERM-U1172, Centre Hospitalier Universitaire de Lille, Fédératif Hospitalo-Universitaire Precise, Lille, France; 12Department of Neurology, Institute of Translational Neurology, University of Münster, Münster, Germany; 13Ares Trading SA, Eysins, Switzerland (an affiliate of Merck KGaA)


Gaps in current evidence and guidance leave clinicians with unanswered questions on the use of cladribine tablets for the treatment of multiple sclerosis (MS) during the COVID-19 pandemic, particularly relating to COVID-19 vaccination. We describe a consensus-based program led by international MS experts with the aim of supplementing current guidelines and treatment labels by providing timely recommendations relating to COVID-19 vaccination and the use of cladribine tablets in clinical practice.

Design and Method(s):

A steering committee (SC) of 10 international MS experts identified seven clinical questions to answer concerning the use of cladribine tablets and COVID-19 vaccination, which addressed issues relating to patient selection, timing and efficacy, and safety. Clinical recommendations addressing each question were drafted using available evidence combined with expert opinion from the SC. An extended faculty of 28 MS experts, representing 19 countries, in addition to the SC members, voted on the recommendations. Consensus on recommendations was achieved when ≥75% of respondents expressed an agreement score of 7–9, on a 9-point scale.


Consensus was achieved on all 13 recommendations. Clinical recommendations are provided on whether all patients with MS receiving cladribine tablets should be vaccinated against COVID-19, and whether they should be prioritized; the timing of vaccination around dosing of cladribine tablets (i.e., before and after a treatment course); and the safety of COVID-19 vaccination for these patients.


There was overwhelming consensus that the risks of COVID-19 outweigh risks of vaccination in people with MS who are being treated with cladribine tablets, and all people with MS treated with cladribine tablets should be vaccinated against COVID-19 as soon as possible, unless they have a contraindication. The consensus provides timely guidance on patient selection, timing, efficacy, and safety of COVID-19 vaccination in patients receiving cladribine tablets, which is relevant to decision-making in everyday clinical practice.