Background. ABO type B and O kidney transplant candidates have increased difficulty identifying a compatible donor for living donor kidney transplantation (LDKT) and are harder to match in kidney paired donation registries. A2-incompatible (A2i) LDKT increases access to LDKT for these patients. To better inform living donor selection, we evaluated the association between A2i LDKT and patient and graft survival. Methods. We used weighted Cox regression to compare mortality, death-censored graft failure, and all-cause graft loss in A2i versus ABO-compatible (ABOc) recipients. Results. Using Scientific Registry of Transplant Recipients data 2000–2019, we identified 345 A2i LDKT recipients. Mortality was comparable among A2i and ABOc recipients; weighted 1-/5-/10-y mortality was 0.9%/6.5%/24.2%, respectively, among A2i LDKT recipients versus 1.4%/7.7%/22.2%, respectively, among ABOc LDKT recipients (weighted hazard ratio [wHR], 0.811.041.33; P = 0.8). However, A2i recipients faced higher risk of death-censored graft failure; weighted 1-/5-/10-y graft failure was 5.7%/11.6%/22.4% for A2i versus 1.7%/7.5%/17.2% for ABOc recipients (wHR in year 1 = 2.243.565.66; through year 5 = 1.251.782.53; through year 10 = 1.151.552.07). By comparison, 1-/5-/10-y wHRs for A1-incompatible recipients were 0.631.966.08/0.390.942.27/0.390.831.74. Conclusions. A2i LDKT is generally safe, but A2i donor/recipient pairs should be counseled about the increased risk of graft failure and be monitored as closely as their A1-incompatible counterparts posttransplant.

Background. Following the outbreak of coronavirus disease 2019 (COVID-19) in the United States, the number of kidney waitlist additions and living-donor and deceased-donor kidney transplants (LDKT/DDKT) decreased substantially but began recovering within a few months. Since then, there have been several additional waves of infection, most notably, the Delta and Omicron surges beginning in August and December 2021, respectively. Methods. Using SRTR data, we compared observed waitlist registrations, waitlist mortality, waitlist removal due to deteriorating condition, LDKT, and DDKT over 5 distinct pandemic periods to expected events based on calculations from preepidemic data while accounting for seasonality and secular trends. Results. Although the number of daily waitlist additions has been increasing since May 2020, the size of the active waitlist has consistently declined, reaching a minimum of 52 556 on February 27, 2022. The recent Omicron surge knocked LDKT from 25% below baseline (incidence rate ratio [IRR] = 0.69 0.75 0.81 ) during the Delta wave to 38% below baseline (IRR = 0.58 0.62 0.67 ). DDKT, however, was less affected by the Omicron wave (IRR = 0.85 0.89 0.93 and 0.88 0.92 0.96 during the Delta and Omicron waves, respectively). Waitlist death decreased from 56% above baseline (IRR = 1.43 1.56 1.70 ) during Delta to 41% above baseline during Omicron, whereas waitlist removal due to deteriorating condition remained at baseline/expected levels during the Delta wave (IRR = 0.93 1.02 1.12 ) and the Omicron wave (IRR = 0.99 1.07 1.16 ). Conclusions. Despite exceptionally high COVID-19 incidence during the Omicron wave, the transplant system responded similarly to prior waves that imposed a lesser disease burden, demonstrating the transplant system’s growing adaptations and resilience to this now endemic disease.