In solid organ transplant recipients (SOTRs), 2-dose mRNA vaccination offers suboptimal protection, with similar infection rates and modestly decreased mortality when compared with unvaccinated SOTRs.1,2 Encouragingly, a third vaccine dose improves neutralization against variants of concern for some SOTRs, yet others do not mount an antibody response even following a fourth dose.3-6 It is unclear whether continued immune priming can augment vaccine immunogenicity in this population, and the benefit of a fifth dose (D5) remains unstudied. We describe 18 SOTRs who received a D5 vaccine between July 26, 2021, and December 11, 2021, and were followed through January 14, 2022.