BACKGROUND Patients with Multiple Sclerosis (MS) and Neuromyelitis Optica Spectrum Disease (NMOSD) may have higher risk of contracting COVID-19 infection than the general population which may be due to disease modifying drugs (DMDs), disability and other comorbidities leading to immune system dysfunction. Not only COVID-19 may aggravate or lead to progression of MS, re-infection and different amount of antibody formation against COVID-19 may also be seen in these population. OBJECTIVE We investigated the clinical characteristics of COVID-19 infection and the relationship between using DMDs and other possible contributing factors with the rate and severity of COVID-19 infection in 2878 MS/NMOSD patients. METHODS Within 12 months follow-up, we also assessed the relapses, progression of the disease (MS), COVID-19 reinfection and sero-positivity of the patients. RESULTS Our study demonstrated that MS and NMOSD patients are generally not at a higher risk of COVID-19 infection compared to general population. Although, some patients treated with DMDs such as Rituximab, Fingolimod and Natalizumab were at a higher risk of COVID-19 infection or even re-infection compared to other DMDs. CONCLUSIONS It is probable that some drugs could have relatively protective effects. We had limited report of exacerbation of MS and NMOSD among confirmed cases not close to the infection time, at least in our short-term follow-up.

BACKGROUND Patients with Multiple Sclerosis (MS) and Neuromyelitis Optica Spectrum Disease (NMOSD) may have higher risk of contracting COVID-19 infection than the general population which may be due to disease modifying drugs (DMDs), disability and other comorbidities leading to immune system dysfunction. Not only COVID-19 may aggravate or lead to progression of MS, re-infection and different amount of antibody formation against COVID-19 may also be seen in these population. OBJECTIVE We investigated the clinical characteristics of COVID-19 infection and the relationship between using DMDs and other possible contributing factors with the rate and severity of COVID-19 infection in 2878 MS/NMOSD patients. METHODS Within 12 months follow-up, we also assessed the relapses, progression of the disease (MS), COVID-19 reinfection and sero-positivity of the patients. RESULTS Our study demonstrated that MS and NMOSD patients are generally not at a higher risk of COVID-19 infection compared to general population. Although, some patients treated with DMDs such as Rituximab, Fingolimod and Natalizumab were at a higher risk of COVID-19 infection or even re-infection compared to other DMDs. CONCLUSIONS It is probable that some drugs could have relatively protective effects. We had limited report of exacerbation of MS and NMOSD among confirmed cases not close to the infection time, at least in our short-term follow-up.