For a study, the researchers sought to characterize antibody and T-cell responses to the 3 SARS-CoV-2 vaccinations now available in the United States (US) in patients with relapsed multiple sclerosis (RMS) who were using ozanimod or other disease-modifying treatments (DMTs). According to the research, RMS patients on specific DMTs might have a reduced humoral response to COVID-19 vaccines. Sphingosine-1-phosphate (S1P) receptor modulators may manage RMS by sequestering circulating lymphocytes, raising doubts about ozanimod and other S1P receptor modulators’ vaccine response in RMS. Patients with RMS vaccinated against COVID-19 will be followed in the prospective observational experiment. The proportion of participants treated with ozanimod who have SARS-CoV-2 anti-spike IgG positive (Elecsys® Anti-SARS-CoV-2) 4 weeks following complete vaccination relative to pre-vaccination levels was the primary goal. RMS patients were recruited online (under the care of multiple neurologists). All study-related procedures were conducted at the patient’s home to ensure a geographic spread across the United States. The antibody and T-cell responses of 60 patients (30 treated with ozanimod and 30 treated with other FDA-approved RMS DMTs) will be examined before and 28 days after complete vaccination. In addition, until a year has passed since the second (or sole) vaccine dosage, all subjects will complete follow-up questionnaires every 3 months. RMS patients treated with ozanimod demonstrated an antibody and T-cell response to the 3 COVID-19 vaccinations available in the United States in the study. The study was still underway, with a 48-week follow-up scheduled for December 2022.