A retrospective evaluation of seroconversion after COVID-19 during the early Omicron wave in fully vaccinated multiple sclerosis patients receiving anti-CD20 therapies

BACKGROUND: Patients with multiple sclerosis (MS) are commonly treated with anti-CD20 therapies. Reduced seroconversion following COVID-19 vaccination in patients receiving certain anti-CD20 therapies has been reported; however, the immune response following natural infection is poorly characterised. This study aimed to retrospectively evaluate COVID-19 antibody responses after vaccination and natural infection in patients treated with anti-CD20 therapies. METHODS: We performed a retrospective review evaluating COVID-19 seroconversion and anti-spike glycoprotein antibody titres in double-vaccinated patients with MS, or related neuroinflammatory conditions, treated with anti-CD20 therapies (N = 30) with a confirmed history of natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (n = 14) or without infection (control; n = 16). This single-centre study was performed at the Yale Multiple Sclerosis Center, where patients treated with anti-CD20 therapies (ocrelizumab, n = 21; rituximab, n = 5; ofatumumab, n = 4) were systematically checked for SARS-CoV-2 anti-spike antibody levels throughout the pandemic. Data were collected from March 2020 to March 2022. All patients had received at least two doses of a Food and Drug Administration (FDA)-approved COVID-19 vaccine. Qualitative anti-spike antibody seropositivity was determined based on test-specific laboratory reference ranges. For a subset of patients (n = 18), quantitative anti-spike antibody levels were assessed via DiaSorin LIAISON® chemiluminescence immunoassay (positive titre was defined as ≥ 13). Vaccination and infection dates were also recorded, and patients were monitored for adverse COVID-19-related health effects. RESULTS: Overall, 15/30 (50.0%) patients seroconverted following double vaccination. After infection, 13/14 (92.9%) seroconverted, while 6/16 (37.5%) uninfected patients seroconverted after vaccination. For the 18 patients with quantitative anti-spike antibody titres, mean titre post-vaccination was 37.4. Mean antibody titres were significantly higher after infection: 540.3 versus 20.1 in the control group (p < 0.05). Of the 14 infected patients, 13 had mild COVID-19 symptoms and one was asymptomatic. No hospitalisations or deaths were reported. CONCLUSIONS: This study reports that SARS-CoV-2 anti-spike antibody titres in double-vaccinated MS patients treated with anti-CD20 therapies were significantly increased post-infection compared with the control group. Patients treated with anti-CD20 therapy who had confirmed infections displayed mild or asymptomatic infection. These results provide reassurance that anti-CD20 therapies in double-vaccinated patients do not preclude an appropriate SARS-CoV-2 antibody response post-infection.