Low Risk of Prolonged SARS-CoV-2 Shedding and Molecular Evolution in Kidney Transplant Recipients During the Omicron Era: A Prospective Observational Study

The aim of this prospective study was to assess the duration of culture-viable SARS-CoV-2 and to monitor the emergence of mutations in a cohort of 23 kidney transplant recipients (KTRs) from June 2022 to June 2023. Combined nares/oropharyngeal swabs were collected weekly starting as soon as possible after symptom onset. The time from symptom onset to a negative culture was 11 days (interquartile range, 8-14), while the time to negative reverse transcriptase quantitative polymerase chain reaction was 18 days (interquartile range, 15-30). Beyond the first swab, 21.7% had a positive culture, and 8.7% replicated viable virus for longer than 30 days. T cell depletion (rate ratio, 2.5; 95% confidence interval [95% CI], 1.9-3.3; P < .001) and time from transplantation (rate ratio, 0.93; 95% CI, 0.90-0.97; P = .006) were associated with the time of viable virus shedding. A cycle threshold value of 24.2 demonstrated a 91.3% negative predictive value of viability (95% credible interval [95% CrI], 76-100). The odds of viability decreased by 69% per week of infection (odds ratio, 0.31; 95% CrI, 0.12-0.76). Overall, ribonucleic acid sequencing did not show accelerated molecular evolution though mutation rate could be increased in molnupiravir-treated KTRs. In conclusion, viable SARS-CoV-2 is eliminated rapidly, the risk of virus evolution is low, and prolonged self-isolation is generally unnecessary for most KTRs.