Impact of COVID-19 in Solid Organ Transplant Recipients

Lara Danziger-Isakov; Emily A. Blumberg; Oriol Manuel; Martina Sester


American Journal of Transplantation. 2021;21(3):925-937. 

In This Article

SARS-CoV-2 Testing in Transplant Recipients

Direct SARS-CoV-2 assays and information on infectivity in the setting of organ transplantation are essential to identify infected patients, to discontinue isolation and to screen potential donors, candidates and recipients. Specimen sources include nasopharyngeal, nasal or throat swabs, and bronchoalveolar lavage (BAL) with polymerase chain reaction (PCR) platforms or antigen testing employed. With early testing platforms, negative initial testing did not eliminate the possibility of infection. In one cohort, as many as 8% of SOT recipients with initial negative SARS-CoV-2 PCR had subsequent positive testing.[84]

Evidence from the general population including viral culture assays suggests that PCR positivity from nasopharyngeal swabs declines within 3 weeks, whereas infectivity already decreases within 8 days after symptom onset, respectively.[108–110] Longer PCR positivity may apply for BAL or sputum samples. Interestingly, prolonged duration of positive PCRs from nasopharyngeal swabs was reported fairly early in the pandemic in SOT recipients. A positive PCR was discovered in a heart transplant recipient 35 days after onset of symptoms, and in a kidney transplant recipient 63 days after onset despite positive serologic response on day 47.[18,19] Other cases in kidney and lung recipients have confirmed prolonged PCR positivity at more than 30 days post-symptom onset,[21] with up to 25% of cases in a French cohort.[20] Additional data regarding prolonged PCR positivity and potential transmission of replication-competent SARS-CoV-2 from SOT recipients are needed to address issues around infection prevention and isolation practices, as correlation between PCR positivity and infectivity in SOT recipients remains uncertain. Rapid antigen tests with acceptable performance characteristics are now becoming available; this may improve screening time in some settings.[111]

Indirect assays such as SARS-CoV-2-specific serology and cellular immunity have been evaluated in limited circumstances in SOT recipients. Serologic response to SARS-CoV-2 has been reported in cases and series of kidney and lung recipients.[21,112] In a small study among seven patients admitted to the hospital, all developed IgG against the nucleocapsid protein of SARS-CoV-2 between 5 and 27 days after the onset of symptoms.[21] In 116 samples from 35 kidney transplant recipients either IgM or IgG against SARS-CoV-2 recombinant nucleocapsid and spike antigens were positive in all survivors and samples more than 14 days after symptom onset, and sustained through day 59.[20] Data from the general population suggest that SARS-CoV-2-specific CD4 and CD8 T cells are induced shortly after infection, contributing to viral control,[6,10] which also was observed in a case report of a renal-pancreas recipient[113] and a small series of kidney transplant recipients.[114] However, no data are available on the stability of cellular immunity in the long term. As new data continue to emerge, understanding the role of serology and specific T cells in defining prior infection or in predicting outcome, recovery, and protection from reinfection will be essential.