Abstract
The excess mortality of COVID-19 solid organ transplant recipients (SOTRs) throughout the pandemic remains unclear. This prospective cohort study based on the Japanese nationwide registry included 1,632 SOTRs diagnosed with COVID-19 between February 1, 2020, and July 31, 2022, categorized based on dominant phases of variants of concern (VOC): Waves 1-3 (Beta), 4 (Alpha), 5 (Delta), 6 (Omicron BA.1/BA.2), and 7 (Omicron BA.5). Excess mortality of COVID-19-affected SOTRs was analyzed by calculating standardized mortality ratios (SMRs). Overall, 1,632 COVID-19-confirmed SOTRs included 1,170 kidney, 408 liver, 25 lung, 20 heart, 1 small-intestine, and 8 multiorgan recipients. Although disease severity and all-cause mortality decreased as VOC transitioned, SMRs of SOTRs were consistently higher than those of the general population throughout the pandemic, showing a U-shaped gap that peaked toward the Omicron BA.5 phase; SMR (95% CI): 6.2 (3.1-12.5), 4.0 (1.5-10.6), 3.0 (1.3-6.7), 8.8 (5.3-14.5), and 21.9 (5.5-87.6) for Waves 1-3 (Beta), Wave 4 (Alpha), Wave 5 (Delta), Wave 6 (Omicron BA.1/2), and Wave 7 (Omicron BA.5), respectively. In conclusion, COVID-19 SOTRs had greater SMRs than the general population across the pandemic. Vaccine boosters, immunosuppression optimization, and other protective measures, particularly for older SOTRs, are paramount.