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Patients with multiple sclerosis (MS) who use disease-modifying therapies (DMTs) had a 44% lower chance of developing new neurological MS symptoms during a COVID-19 infection, according to a national, community-based, prospective cohort study published in Multiple Sclerosis and Related Disorders.

Although there are safety concerns about using DMTs during the COVID-19 pandemic due to their immunosuppressive actions, this study provides data to inform clinical decision-making regarding changing or delaying the treatment of MS with DMTs. While patients with MS may be slightly more susceptible to contracting COVID-19 while on immunosuppressive DMTs, the exacerbation of existing or development of new MS symptoms following COVID-19 infection may last longer than 3 months without DMTs. 

Garjani et al used the United Kingdom MS Register to survey 978 people with MS and COVID-19. Of those, 404 responded, at a median of 14 weeks after their COVID-19 diagnosis. Among the respondents, 230 (57%) reported an MS exacerbation during a COVID infection. Eighty-two people developed new MS symptoms, 207 experienced worsening of pre-existing MS symptoms, and 59 reported both. Approximately 62% (144) of the individuals who experienced an exacerbation of their MS symptoms did not return to baseline within 3 months of reporting COVID-19 infection. 

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Taking DMTs reduced the probability of developing new neurological MS symptoms (OR 0.556, 95% CI, 0.316-0.978) including problems with weakness, paresthesias, balance, vertigo, spasms, bladder or bowel dysfunction, vision, fatigue, memory, mobility, speech, swallowing, and tremors. While the researchers did not conduct formal testing of the relationship between individual DMTs and prevention of new MS symptoms, they observed that a higher proportion of patients who did not report new MS symptoms were taking fingolimod, ocrelizumab, or cladribine during their COVID infection, compared with those who developed new symptoms.

Limitations of this study included patient recall bias, lack of objective neurological examination (due to pandemic restrictions) to confirm relapses and new MS symptoms, lack of paraclinical tests to truly distinguish MS deterioration from systemic symptoms of COVID-19 especially fatigue and cognitive problems, and lack of a control group of people with MS without COVID-19 which prohibited assessment of absolute risk of MS exacerbations associated with COVID-19.  

Co-author Nikos Evangelou, PhD, recommended “for the vast majority of [MS] patients, treatment with DMT needs to be continued as there is a very small extra risk from COVID when patients are on DMT. The fear of immune suppression seems to be higher than the real risk.”

“This research is building on the theme of environmental influences for MS relapses. I hope we will have more research exploring these dynamics,” he added.


Garjani A, Middleton RM, Hunter R, et al. COVID-19 is associated with new symptoms of multiple sclerosis that are prevented by disease modifying therapies. Mult Scler Relat Disord. Published online May 4, 2021. doi:10.1016/j.msard.2021.102939