SARS-CoV-2 RNA in Explant Lung Tissue from Patients with COVID-19 ARDS

PURPOSE: Lung transplantation (LTx) can be considered in patients suffering from COVID-19 ARDS where lung recovery is unlikely. Exclusion of ongoing viral infection is an important condition to prevent COVID-19 transmission after LTx. Therefore, repeated negative SARS-CoV-2 PCR of bronchoalveolar lavage (BAL) samples is recommended. Using lungs removed during LTx for COVID-19 ARDS we aim to provide insight in the reliability of PCR on BAL samples for detection of SARS-CoV-2. METHODS: In two COVID-19 ARDS patients (A & B), we performed bilateral LTx 76 and 85 days after onset of COVID-19 symptoms. At least two PCR negative BAL samples were obtained prior to LTx: 33 and 73 days after onset in patient A; 61, 74 and 83 days after onset in patient B. After LTx, the removed right native lung was inflated and frozen. Per lung, 10 frozen biopsies from different regions in the three lobes were taken. For each biopsy, PCR targeting the SARS-CoV-2 Nucleocapsid (N) and subgenomic Envelope (sgE) RNA was performed. RESULTS: N-gene RNA was detected in both the upper, middle and lower lobes (figure). In patient A, 7 out of 10 biopsies were positive (Cycling threshold (Ct)=32.9-36.0). In patient B, 9 out of 10 biopsies were positive (Ct=29.9-33.1). PCR did not detect sgE-gene RNA in any biopsy. PCR Ct-values above 28 for N-gene RNA and no detection of sgE-gene RNA suggest absence of ongoing viral infection. After LTx, repeated PCR on BAL did not detect viral RNA in either recipient and both patients are currently doing well. CONCLUSION: PCR on BAL fluid is considered a sensitive method to detect SARS-CoV-2. However, BAL sampling does not provide a complete picture on viral presence in the lung. After repeated negative PCR on BAL fluid, we proceeded with LTx in two patients with COVID-19 ARDS. Different lung regions still carried viral RNA, but there are no arguments that viral infection was still going on. Our understanding on the behavior and clinical relevance of persisting SARS-CoV-2 RNA, deep in the lung, is not complete and warrants further research.