The association of upper respiratory infections with neuro-radiological course and attack rate of multiple sclerosis: Results from a large prospective cohort.

Background: Although upper respiratory infections (URIs) are linked to multiple sclerosis (MS) attacks, SARS-COV2 has not been compared to URIs for attack rates.

Objectives: This study aimed to evaluate the attack rate and the results of neuroimaging in MS patients with URIs caused by COVID-19 and non-COVID-19 infections (NC-URI).

Methods: From May 2020 to April 2021, we followed 362 patients with relapsing-remitting MS in a prospective cohort design. Patients were monitored regularly every 12 weeks; an magnetic resonance imaging (MRI) scan was performed at enrollment and every time a relapse occurred. Poisson analysis was used to determine exacerbation rate ratios (RR) and the MRI parameters were tested using chi-square analysis.

Results: 347 patients with an average age of 38 and a female ratio of 86% were included. A RR of 2.24 (p < 0.001) was observed for exacerbations during the at-risk period (ARP). Attacks related to COVID-19 (RR = 2.13, p = 0.001) and NC-URIs (RR = 2.39, p < 0.001) were comparable regarding the increased risk of exacerbation (p = 0.62). Exacerbations within or outside the ARP did not significantly alter the number of baseline GAD-enhancing lesions (p > 0.05 for both).

Conclusion: COVID-19 has been shown to increase the risk of MS exacerbations, like other viral URIs.