Purpose: We aim to analyze the proportion and level of coronavirus disease 2019 (COVID-19) seropositivity in patients with systemic lupus erythematosus (SLE) and explore factors associated with lower anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (S-RBD) antibody levels.
Materials and methods: A cross-sectional study involving patients with SLE was conducted. We included those aged 18-60 years, either unvaccinated or had received inactivated vaccine (CoronaVac; Sinovac Biotech Ltd., China). Furthermore, participants were tested for anti-SARS-CoV-2 S-RBD antibody levels and SARS-CoV-2 surrogate virus neutralization test, and comparative test analysis was employed.
Results: This study included 159 subjects of whom 92 and 67 were SLE subjects and controls, respectively. Significantly higher seropositive results were noted in patients with SLE receiving vaccine (96.9% versus 3.1%). Unvaccinated SLE patients receiving cyclophosphamide (CYC) had higher anti-RBD levels compared to unvaccinated SLE patients not receiving CYC (23.81 [interquartile range (IQR), 2.26-78.85] versus 2.13 [IQR, 0.1-12.5]), whereas vaccinated SLE patients receiving CYC had lower anti-RBD levels compared to vaccinated SLE patients not receiving CYC (15.5 [IQR, 6.62-35.09] and 69.77 [IQR, 17.48-201]). In the vaccinated SLE group, a lower value of anti-SARS-CoV-2 RBD antibody levels was observed in patients receiving mycophenolate mofetil and those with chronic kidney disease. No correlation was noted between disease activity and organ involvement with lower antibody response.
Conclusion: The increase in COVID-19 antibody levels in patients with SLE may be affected by exposure to hospital settings and vaccine. Furthermore, CYC treatment is associated with lower antibody response after receiving vaccine.
Keywords: Anti–SARS-CoV-2 S-RBD antibody; CoronaVac; Cyclophosphamide; Neutralization test; Systemic lupus erythematosus.
© Korean Vaccine Society.