HLTRs without a previously confirmed coronavirus disease 2019 infection (N = 212) were recruited as previously described.1 Immunosuppression regimens were self-reported, and participants were stratified into 4 groups based on reported total daily dose of MMF: zero MMF, low dose (<1000 mg/d), moderate dose (1000–2000 mg/d), and high dose (≥2000 mg/d). Patients receiving mycophenolic acid were excluded. Antispike antibody testing was performed at 1, 3, and 6 mo after dose 2 using commercially available assays, as previously described.1,3