million. The hygienic protective measures and test capacities were thus still in the process of development at our institution. These circumstances promoted the risk of nosocomial infection with SARS-CoV-2, which unfortunately was the case in our patient. A nasopharyngeal swab confirmed infection by PCR on March 25 ( Figure 1B ). Waiting list status was changed to "nontransplantable," and he was transferred to a COVID-19 isolation ward where he developed increasing malaise and dry cough.
Overall the patient had a mild course of COVID-19. Vital signs remained stable and lab work was unremarkable except for mild lymphopenia. In the absence of dyspnea, a thoracic CT scan was not performed. The patient received no COVID-19-specific or antiviral therapy. SARS-CoV-2 RNA remained detectable in routine swabs after seroconversion (anti-SARS-CoV-2 IgG and IgA antibodies) had occurred on the 21st day after onset of symptoms ( Figure 1A ). Persistence of viral RNA shedding despite seroconversion was recently described. 1 It was not until the 31st and 32nd day of illness that nasopharyngeal swabs showed negative PCR results.
The patient was free of COVID-19 symptoms, thus isolation was ended and he was transferred to a normal ward without isolation.
The questions of when the patient would be able to be transplanted and what additional risks the recent diagnosis of COVID-19 would pose were discussed at the interdisciplinary transplantation conference under consideration of the sparse existing data on this F I G U R E 1 Timeline of test results for (A) antibody levels and (B) viral load and live virus cell culture. (A) Semiquantitative results using the Euroimmune Anti-SARS-CoV-2-ELISA for IgG and IgA targeting the spike domain S1 are indicated (result interpretation ranges as indicated by the manufacturer: negative = 0-0.8 [cyan line], borderline = 0.8-1.1, positive = above 1.1 [blue line]; the coefficient of variation is <10% for positive samples, as stated by the manufacturer). Swab technique and type used were the same for all tests. Neutralizing antibody titers from a microneutralization assay are shown on the right y-axis. The lower assay cut-off of 1:10 is indicated by the red line. (B) Viral load results (black triangles) are shown on a logarithmic scale with copy number estimates expressed as SARS-CoV-2 RNA copies per ml respiratory sample using the CDC N1 reaction as previously described. 11 Copy numbers were calculated based on a standard curve using serial dilutions of a plasmid containing the N-gene with known copy numbers (IDT) on a Roche Light Cycler II 480. High variability of test results around day 60 most likely arise from suboptimal swab technique. Live virus cell culture results were all negative, dates are indicated by red arrows on the x-axis topic at the time. 2, 3 Due to the complete recovery of the patient with proven seroconversion and two negative PCR results for viral RNA, the burden of liver disease in this seriously ill patient was deemed to outweigh potential risks of the resolved SARS-CoV-2 infection.
On 1st of May, 36 days after onset of COVID-19 symptoms and 15 days after documented seroconversion, the patient received an organ offer of a 26-year-old brain dead donor, tested negative for SARS-CoV-2. Preoperatively, our patient remained asymptomatic and afebrile. Laboratory testing showed no inflammatory changes, and in particular white blood cell count was normalized. To detect residual signs of COVID-19, a thoracic CT was performed prior to surgery, which showed sporadic and slight thickening of bronchial walls, but no radiographic signs indicative of COVID-19 pneumonia. As this patient appears to be the first one-to our knowledge-to receive a liver transplant shortly after resolved COVID-19 infection, we sought to gain more insight into the effect the procedure and immunosuppression might have on viral status and antibody titers. To our surprise, SARS-CoV-2 RNA was recurrently detected in upper respiratory swabs during routine testing at viral loads comparable to pretransplantation levels on days 27, 33, and 38 after seroconversion, while the patient remained asymptomatic and afebrile the whole time. To further explore this unusual case, we also repeated antibody testing, which showed partial seroreversion with now seronegativity for anti-SARS-CoV-2 IgG antibodies with persistingly low levels of IgA.
Subsequent testing returned only borderline positive results for IgG (blue line, Figure 1A ) and very low positive IgA levels (purple line, Figure 1A ). Neutralizing antibody levels, measured using a microneutralization assay (red line, Figure 1A) , also declined markedly after liver transplantation from mid-low range titer of 1:40 to very low 1:10 titers. However, viral infectivity appeared to be absent as four subsequent attempts of live viral isolation in cell culture all returned negative (red arrows, Figure 1B ). We ruled out reinfection with a different viral strain by near-full length SARS-CoV-2 genome sequencing of samples before and after liver transplantation, which proved to be identical (data not shown). After two further negative swab results, the patient was discharged on postoperative day 33 with excellent liver function and no COVID-19 symptoms. He continued to show no signs of COVID-19 by the time this article was written.
This case addresses the questions of if and when a patient can be safely transplanted after recovery from COVID-19. In approaching this question, we considered two aspects: first, is the patient at increased risk for recurrence of the disease, potentially in a severe form, during the perioperative phase and second, is the previously acquired immunity against COVID-19 compromised by the treatment?
Although the general outcome of liver transplantation was fa- On the other hand, a profound virus-specific T cell response elicited by SARS-CoV-2 was recently discovered in a large cohort.
SARS-CoV-2 reactive CD4 + and CD8 + T cells were detected in 100% and 70% of convalescent patients, respectively. 4 Whether this reaction leads to a long-lived memory T cell response that confers longterm immunity against the disease is unclear, although this has been shown to be the case in SARS-CoV-1. 8 Unfortunately, we did not assess T cell reactivity in our patient. Thus it remains uncertain, if this aspect of immunity is present in our patient and if so, whether it is jeopardized by the immunosuppression he receives. From the sparse literature on the topic it is known that memory T cell function against other viruses, such as CMV, seems not to be affected by aggressive induction regimens of immunosuppression. 9 The possibility of reinfection after recent COVID-19 remains controversial despite over 5 000 000 patients who recovered from the disease worldwide. This observation has been sustained by the lack of evidence of reinfection in rhesus macaques that were challenged again with the virus after convalescence. 10 Although our patient tested positive on nasopharyngeal swabs and sputum again following transplantation, re-infection appears unlikely as the patient suffered no symptoms, viral sequencing showed identical RNA sequences, and the virus failed to replicate in cell culture. If the rapid decline in protective antibody levels we observed in our patient truly reflects detrimental effects on immunity is unknown, as memory T cell response might still be unaffected and potentially prove to be the more important pillar of immunity against COVID-19. In summary, despite worrisome aspects in the postoperative course, we are convinced that the recent COVID-19 did not put the patient at an increased risk during the liver transplantation he urgently needed.
Open access funding enabled and organized by ProjektDEAL.
The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
https://orcid.org/0000-0002-0981-4049
Nikolaus Börner https://orcid.org/0000-0002-1310-6600
Markus Guba https://orcid.org/0000-0002-7778-8401