Bergamaschi R, Ponzano M, Schiavetti I, et al. - According to some studies, air pollution, usually evaluated by thin particular matter with diameter below 2.5 µg/m3 (PM2.5), could be a contributor to severe COVID-19 courses, as well as have a role in the onset and evolution of Multiple Sclerosis (MS). The links between PM2.5 and COVID-19 severity among patients with MS (PwMS) were investigated in this retrospective observational study.

• Using data from an Italian web-based platform (Musc-19) which incorporates PwMS with COVID-19, a total of 1,087 patients with a COVID-19 positive test were analyzed.

• Among participants, 13% needed hospitalization and 2% were admitted to intensive care unit or died.

• An elevated risk of worst COVID-19 course was observed in relation to higher concentrations of PM2.5, in multivariate analysis, (OR=1.90).

• Unfavorable course of COVID-19 in PwMS is even if explained by various other factors, the role of air pollutants is still necessary to be considered and further explored.