Multiple sclerosis (MS) is a chronic immune-mediated neurodegenerative disease characterized by neuroinflammation, demyelination, and axonal injury within the central nervous system (Lamb, 2022; Syed, 2018). Patients with MS are at higher risk of viral infections due to both the immunomodulatory effects of MS and the immunosuppressive medications used for treatment (Lamb, 2022; Syed, 2018). Immune-mediated interactions between MS and viral infections have been reported (Sedighi et al., 2022). Some patients with MS may be especially susceptible to severe SARS-CoV-2 infection due to underlying comorbidities and anti-CD20 therapies (Barzegar et al., 2021). It is unclear whether SARS-CoV-2 infection predisposes MS patients to persistent adverse outcomes. Identifying risk factors for long-term adverse outcomes may enhance provider awareness for vulnerable individuals with MS following COVID-19.

One hallmark of severe COVID-19 is pathologic hyperinflammation (Webb, 2021; Webb et al., 2020), which could result in increased long-term MS disease activity (Webb et al., 2020) and exacerbate immune-mediated neurotoxicity (Gupta and Weaver, 2021), thereby accelerating MS disease progression. Indicators of MS disease activity include MS relapses, prescriptions of steroids to treat acute relapses (Martinez-Caceres et al., 2002), changes in disease modifying therapy (DMT) prescription (Maurer et al., 2019), or new occurrences of optic neuritis (ON) (Dhanapalaratnam et al., 2022), cerebellar deficits (Edwards et al., 2022), increase in expanded disability status scale (EDSS) score, or MRI findings (Inglese and Petracca, 2018). Some studies have reported that MS patients with vs. without COVID-19 had worse longer-term MS disease activity (Conway et al., 2022; Peeters et al., 2023; Rahmani et al., 2023), while other studies did not (Andersen et al., 2023; Babtain et al., 2022; Bsteh et al., 2022; Etemadifar et al., 2022, 2021; Montini et al., 2023; Vercellino et al., 2023). Most studies have been limited to less than one year post COVID-19 follow-up, which could have contributed to discordant findings.

The goal of this study was to evaluate available long-term outcomes of patients with MS infected with SARS-CoV-2 up to 3.5 years post-acute infection within the Montefiore Health System which serves a large low-income, diverse population in the Bronx and its environs. The Bronx and its environs were an epicenter of the early COVID-19 pandemic and subsequent surges of infection. Long-term outcomes included post-COVID-19 all-cause mortality, development of optic neuritis, change in DMT, MS relapses, steroid infusion to treat relapse, cerebellar deficits, and all-cause hospitalizations post SARS-CoV-2 infection.