Lupus Nephritis During the COVID-19 Pandemic: Challenges and Implications Before, During, and After

<b>Background:</b> Patients with systemic lupus erythematosus (SLE), particularly those with lupus nephritis (LN), are at increased risk of severe COVID-19 outcomes due to immune dysregulation and immunosuppressive therapy. Renal transplant recipients with prior LN (LN-RTX) combine chronic immunosuppression with residual autoimmune risk. This study aimed to evaluate renal function trajectories and disease activity in LN patients during the COVID-19 pandemic, comparing transplant recipients with conservatively managed patients (LN-CT), and to assess the potential effects of COVID-19 vaccination. <b>Methods:</b> A retrospective cohort of 111 biopsy-confirmed LN patients followed between 2019 and 2023 was analyzed at four time points: pre-pandemic (T0), first pandemic year (T1), second pandemic year (T2), and post-pandemic (T3). Changes in renal function, disease activity markers, and treatment patterns were compared between LN-CT (<i>n</i> = 100) and LN-RTX (<i>n</i> = 11) groups, with additional analysis by vaccination status. <b>Results:</b> Renal function declined significantly in LN-CT (median eGFR: from 76.5 to 66.5 mL/min/1.73 m²; <i>p</i> < 0.001) but remained stable in LN-RTX patients despite higher comorbidity rates. LN activity (proteinuria, erythrocyturia) and glucocorticoid/MMF use decreased over time. Vaccinated patients showed a statistically significant decline in eGFR (<i>p</i> = 0.00046), though causality remains uncertain. <b>Conclusions:</b> Renal outcomes during the pandemic differed by treatment modality, with LN-RTX patients maintaining stable function despite higher risk. Adjusted immunosuppression and vigilant monitoring may have supported these outcomes. Further prospective studies should clarify vaccine-related renal effects in LN populations.