Breakthrough COVID-19 in people with multiple sclerosis on disease modifying treatments: Is it still a severe disease?

ABSTRACT

INTRODUCTION: Disease modifying treatments (DMTs) for multiple sclerosis (MS) are effective in preventing both relapses and disability progression. Highly effective treatments (HETs) are more effective than platform therapy in preventing confirmed disability progression (CDP), when used early. Infections may complicate HETs administration, and their prevention through vaccination is crucial in order to assure the safety of people with MS (pwMS). The aim of the present study is to describe the effect of MS DMTs on COVID-19 vaccination and the risk of breakthrough infection in a cohort of pwMS. MATERIALS AND METHODS: This is a monocentric retrospective observational study conducted at the MS center of the Guglielmo da Saliceto Hospital in Piacenza, Italy. One hundred and fifty-seven (157) pwMS who received two doses of the SARS-CoV-2 vaccine (with 80.3 % receiving a booster dose) were included in the study. RESULTS: fifty-six pwMS (35.7 %) were females, the mean age was 48.6 (SD 12.87) years, and 59 (37.6 %) had at least one comorbidity. Twenty-five (15.9 %) breakthrough infections were observed, with 17 (68.0 %) classified as mild and 8 (32.0 %) as moderate. A multivariable linear regression model confirmed that B-cell suppressor DMTs and EDSS were factors associated with the latest antibody titre. Patients treated with B-cell suppressors exhibited a risk almost four times higher for breakthrough infections compared to other patients, with a hazard ratio (HR) of 3.72 (95 % CI 1.50 - 9.27) (p = 0.005). CONCLUSIONS: B-cell suppressor DMTs are associated with the risk of breakthrough COVID-19 in our cohort, but vaccination fully protected pwMS against severe breakthrough disease.