In a multivariate analysis at Ser1, five factors were found to be independently and significantly associated with the anti-S1 IgG titre: a history of COVID-19, the receipt of at least two doses of vaccine, being on the French national waiting list for kidney transplantation, and female sex were associated with a higher anti-S1 IgG titre, whereas immunosuppressive treatment was associated with a lower anti-S1 IgG titre. The gene discussed is PSMD1; the disease is COVID-19.