Investigating SARS-CoV-2 Antibodies in an Amsterdam Multiple Sclerosis Cohort

Written by: Sean Brady
Edited by: Esther Melamed

Introduction

The presence and quantity of pathogen-specific antibodies (such as SARS-CoV-2) can be an indicator of prior exposure to disease as well as an indicator of how well someone may be able to respond to that pathogen if they encounter it again. In a recent research letter in JAMA by Zoé L. E. van Kempen et al, a group of researchers analyzed SARS-CoV-2 antibodies in a large cohort of patients with multiple sclerosis (MS). This analysis enabled the authors to investigate the prevalence of asymptomatic cases as well as the antibody responses patients with MS on different disease-modifying therapies had to the SARS-CoV-2 infection.

The reason this type of analysis is of interest in an MS cohort is that disease-modifying treatments (DMTs) in MS suppress different parts of the immune system, and thus may impact disease severity and immune responses to COVID-19.  For example, if B cells (antibody producers of the immune system) are depleted as part of MS treatment, the body’s ability to make antibodies to pathogens (such as SARS-CoV-2) could be lowered. 

Patient Cohort and Antibody Results

There were 546 MS patients included in the study by Zoé L. E. van Kempen et al, 71.1% were women and the average age was 46.9 years. Out of this group, 11.7% (64 patients) tested positive for SARS-CoV-2 antibodies. The patients in this study were on one of the following DMTs: Natalizumab, Dimethyl fumarate, Ocrelizumab, Fingolimod, Teriflunomide, Interferon beta, Alemtuzumab, Glatiramer acetate, or post Stem cell transplant. The most common symptom experienced by the antibody-positive group was a loss of taste and/or smell. The data on patients’ symptoms were collected via digital questionnaires filled out the week following antibody testing. 

The main takeaways from the paper

14% of patients with MS who had SARS-CoV-2 antibodies had not experienced any COVID-19 symptoms. This rate is comparable to the asymptomatic COVID-19 rate of 17% in the general population [1]. One limitation of this statistic, the researchers noted, was that people may be more apt to participate in this study if they had been symptomatic for COVID-19, meaning that the number of asymptomatic cases could have been underrepresented here. 

In this cohort, patients on Natalizumab, Dimethyl Fumarate, and Fingolimod were found to have high SARS-CoV-2 antibody levels just like patients who were not on DMTs. In comparison, patients on Ocrelizumab (B cell-depleted) had a much lower SARS-CoV-2 antibody level compared to patients not on DMTs. No conclusions could be drawn about antibody associations with other studied DMTs due to a small patient sample size.

These data imply that SARS-CoV-2 antibody production in patients with MS could be influenced by DMTs, such as B cell depleting therapies. One limitation of this study is the relatively small sample size in the cohort who were SARS-CoV-2 positive and who were on specific DMTs, including B cell depleting therapy. 

Ending Thoughts

This paper highlights the importance of investigating how MS patients on different DMTs may be impacted by COVID-19 with potential implications for responses to COVID-19 vaccinations. This work is also potentially generalizable to other patient groups with rheumatological or cancer conditions who are on immunosuppressive therapies. Overall, this research letter underlies the value and importance of studying how therapies for one disease (i.e. MS) may potentially alter the body’s ability to combat another disease (i.e. COVID-19). Further research and larger studies are needed to better define the risks and benefits of using different DMTs in MS in the era of COVID-19 and how MS patients on different DMTs may respond to getting sick with COVID-19 and to getting COVID-19 vaccines.