LAUSR

COVID-19 vaccines utilizing mRNA technology induce vigorous immuneresponsesandexcellentprotectionagainstdiseaseinimmuno-competentadults. 1 Thedegreeofvaccineefficacyintransplantedindi-viduals remains unknown. Recent studies demonstrated the standard two-dose regimen of the Pfizer-BioNTech BNT162b2 vaccine could yield suboptimal immune responses and incomplete clinical protection in transplanted patients. 2 Semi-quantitative antibody titers for anti-Spike (S) protein receptior-binding domain (RBD) may not fully reflect post-vaccine immune responses. We, therefore, performed an expanded panel of antibody and B cell studies in a transplant recipient during BNT162b2 immunization and following the third vaccination with Ad26.COV2.S (Supplemental methods).