Posttransplant lymphoproliferative disorders (PTLDs), 50%‐80% of which are strongly associated with Epstein‐Barr virus (EBV), carry a high morbidity and mortality. Most clinical/epidemiological/tumor characteristics do not consistently associate with worse patient survival, so our aim was to identify if other viral genomic characteristics associated better with survival. We extracted DNA from stored paraffin‐embedded PTLD tissues at our center, identified viral sequences by metagenomic shotgun sequencing (MSS), and analyzed the data in relation to clinical outcomes. Our study population comprised 69 PTLD tissue samples collected between 1991 and 2015 from 60 subjects. Nucleotide sequences from at least one virus were detected by MSS in 86% (59/69) of the tissues (EBV in 61%, anelloviruses 52%, gammapapillomaviruses 14%, CMV 7%, and HSV in 3%). No viruses were present in higher proportion in EBV‐negative PTLD (compared to EBV‐positive PTLD). In univariable analysis, death within 5 years of PTLD diagnosis was associated with anellovirus (P = 0.037) and gammapapillomavirus (P = 0.036) detection by MSS, higher tissue qPCR levels of the predominant human anellovirus species torque teno virus (TTV; P = 0.016), T cell type PTLD, liver, brain or bone marrow location. In multivariable analyses, T cell PTLD (P = 0.006) and TTV PCR level (P = 0.012) remained significant. In EBV‐positive PTLD, EBNA‐LP, EBNA1 and EBNA3C had significantly higher levels of nonsynonymous gene variants compared to the other EBV genes. Multiple viruses are detectable in PTLD tissues by MSS. Anellovirus positivity, not EBV positivity,was associated with worse patient survival in our series. Confirmation and extension of this work in larger multicenter studies is desirable.

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Since the worldwide outbreak of the COVID-19 pandemic in December 2019, Taiwan has successfully stopped the spread of COVID-19. The policies and works of the epidemic control are a complex and dynamic process. This study applied the methodology of system dynamics to explore the structure of the COVID-19 epidemic control system in Taiwan and analysed its system behaviours. The results show that the system is composed of key subsystems, such as national health insurance and quarantine, combined with government policies. Joint efforts among the central and local governments and the general public have been made to strengthen the quarantine of border entrants, encourage the public to wear masks and employ technology for contact tracing and tracking down those being tested positive with COVID-19. Together with the efficient increase in the capacity of testing and medical treatments, these measures can effectively reach a balance between epidemic control and economic activities.