PSMD1 and systemic lupus erythematosus: Although the titers of anti-RBD and anti-S1 IgG significantly increased following booster doses (3+ doses) in the majority of SLE patients compared to the levels detected after the second dose, median levels remained significantly lower than those in healthy individuals (IgG titre median after 3+ doses: RBD HC = 63k vs SLE = 26.7k; S1 HC = 113.7k vs SLE = 53.5k) (Fig. 1C, Supplementary Fig. 1C).