Analysis of anti-SARS-CoV-2-IgG levels did not reveal a significant difference between SLE patients and C1-INH-HAE controls at T1 [t(52.81) = −0.68; p = 0.49] (Figure 3A) and at T2 [t(67.74) = −0.22; p = 0.825] (Figure 3B). Here, SERPING1 is linked to systemic lupus erythematosus.