Objective:

This study evaluates real-world infection rates for MS patients on long-term immunomodulation during the COVID-19 pandemic.

Background:

Numerous treatments exist for multiple sclerosis (MS); some are immunosuppressive (e.g. anti-CD20 medications), while others relocate immune cells (e.g. natalizumab, S1P agonists) or modulate immune subsets (e.g. fumarates). All disease modifying treatments (DMTs) can put patients at risk of infections, including COVID-19, particularly if used long-term.

Design/Methods:

This is a retrospective, observational study. Electronic medical records of adult MS patients prescribed natalizumab, S1P agonists, or fumarates at Yale were reviewed from January 2013 to August 2022. Cases were included if the DMT of interest was used long-term (>2 years) prior to the start of the pandemic. Those without follow-up or known DMT duration were excluded. Severe infections were defined as those requiring hospitalization. Mild infections were identified through outpatient antibiotic prescriptions or reference to “infection” in the chart. 

Results:

241 charts were reviewed; 177 were retained and 9 were lost to follow-up before the start of the pandemic. There were 109 natalizumab-treated patients, 63 on fumarates and 19 on S1P agonists. During the study period, 50 patients (28.2%) experienced at least one severe infection, with urinary tract infection being the most common (48.2%);146 patients (82.5%) experienced at least one mild infection and 65 patients (38.5%) had COVID-19. Severe infections occurred at an incidence (per 100-patient-years) of 4.8 for natalizumab, 19.0 for fumarates and 15.3 for S1P agonists. COVID-19 infections occurred at an incidence of 13.6 on natalizumab, 13.2 on fumarates and 22.5 on S1P agonists.

Conclusions:

We observed lower rates of severe infection for natalizumab-treated patients compared to oral immunomodulators. Additionally, COVID-19 incidence was higher in this cohort than the general population of New Haven County (10.6 infection / 100-person-years). Data analysis is ongoing and will provide insight into practical risks of long-term immunomodulation.  Funding: Biogen.