Humoral and Cellular Immunity After Vaccination Against SARS-CoV-2 in Relapsing-Remitting Multiple Sclerosis Patients Treated with Interferon Beta and Dimethyl Fumarate

Background/Objectives: The impact of vaccines against SARS-CoV-2 on the immunity of patients with multiple sclerosis (PwMS) is still not fully known. Further clarification could help address medical concerns related to the use of immunosuppressive and immunomodulatory medications, known as disease-modifying therapies (DMTs), in PwMS, as well as ensure adequate protection against severe outcomes of COVID-19. Therefore, the aim of our study was to evaluate the humoral and cellular immune response in PwMS treated with DMTs. Methods: The concentrations of IgG Spike (S) anti-SARS-CoV-2 antibodies and IgG Nucleocapsid (N) anti-SARS-CoV-2 antibodies, as well as interferon-gamma (IFN-γ) titers were analyzed in PwMS groups treated with dimethyl fumarate (DMF), interferon beta (IFN), and healthy control group. Results: Almost 100% of PwMS experienced seroconversion, which resulted from either vaccination and/or prior infection. Additionally, there were no significant differences between the study and control groups in terms of IgG (S) and (N) anti-SARS-CoV-2 antibody levels. However, interferon-gamma titers were lower in both PwMS groups, which may indicate adequate humoral and decreased cellular response to the examined PwMS. Additionally, after the division of the whole study group into two subgroups according to the time since the last vaccination, IgG (S) anti-SARS-CoV-2 and IFN-γ concentrations were significantly lower in the case of patients who were immunized more than 200 days before sample collection. No differences were observed in the case of subgroups in which sample collection was less than 200 days after vaccination when compared to the control group. Conclusions: This could indicate a time-related decrease in immunity in PwMS treated with DMTs.