The ADA-positive rate for ustekinumab in previous reports was 5% (38/743), the negative rate was 47% (351/743), and the inconclusive rate was 48% (354/743) in a study on plaque psoriasis patients treated with ustekinumab for 28–48°weeks, with the final ADA test at week 52 after administration (Armstrong and Read, 2020; Centocor Ortho Biotech Inc, 2020). Here, ADA is linked to psoriasis vulgaris.