Background/Purpose: Patients with systemic lupus erythematosus (SLE) should be more proactive with the administration of the COVID-19 vaccine, as their systemic conditions are prone to developing severe outcomes. However, there are concerns that immunosuppressive agents used in SLE patients could reduce the immune response. Previous data demonstrates that total B-cell depletion impairs the humoral response in patients treated with Rituximab, but there is very limited information about Belimumab. Thus, we aimed to assess the immunogenicity and safety of COVID-19 vaccine in SLE patients treated with Belimumab.

Methods: Between December 14, 2021, and June 17, 2022, patients diagnosed with SLE who were receiving B-cell targeted therapy with Belimumab were recruited. We examined the patients’ inoculation history, and antibody titer was measured in patients who had completed the third dose of COVID-19 vaccine. SARS-CoV-2 antibody titers were determined through semiquantitative anti-SARS-CoV-2 S enzyme immunoassay.

Results: As a result of surveying 21 SLE patients receiving Belimumab, only 10 patients completed up to the 3 doses of COVID-19 vaccine. The mean duration between the last (3rd) vaccination date and the date of sample acquisition was 22.5 weeks, and there was no patient with side effect other than mild myalgia. The antibody titer was positive in all 10 patients, and among them, 8 patients showed a high antibody titer of 250 U/mL or more, and the remaining two patients showed a relatively low antibody titer of 117 U/mL and 112 U/mL, respectively. One patient had been treated with Rituximab within one year and the other was using hydroxychloroquine.

Conclusion: Our findings suggest that Belimumab does not compromise the antibody production from the vaccination. SLE patients with Belimumab need not be reluctant to get the COVID-19 vaccines because of worrying about the humoral response impairment.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sars-cov-2-antibody-formation-after-covid-19-vaccination-in-sle-patients-treated-with-belimumab-single-center-prospective-observational-study/