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Combined with other studies, these data indicate that vaccinated and unvaccinated individuals infected with the Delta variant might transmit infection. Importantly, we show that infectious SARS-CoV-2 is frequently found even in vaccinated persons when specimen Ct values are low.
https://www.medrxiv.org/content/10.1101/2021.07.31.21261387v4.full
Published August 2015
Design and Analysis of Shedding Studies for Virus or Bacteria-Based Gene Therapy and Oncolytic Products The Center for Biologics Evaluation and Research (CBER)/Office of Cellular, Tissue, and Gene Therapies (OCTGT) is issuing this guidance to provide you, sponsors of virus or bacteria-based gene therapy products (VBGT products)1 and oncolytic viruses or bacteria (oncolytic products)2 with recommendations on how to conduct shedding studies during preclinical and clinical development. For purposes of this guidance, the term “shedding” means release of VBGT or oncolytic products from the patient through one or all of the following ways: excreta (feces); secreta (urine, saliva, nasopharyngeal fluids etc.); or through the skin (pustules, sores, wounds). Shedding is distinct from biodistribution because the latter describes how a product is spread within the patient’s body from the site of administration while the former describes how it is excreted or released from the patient’s body. Shedding raises the possibility of transmission of VBGT or oncolytic products3 from treated to untreated individuals (e.g., close contacts and health care professionals). This guidance represents FDA’s current thinking on how and when shedding data should be collected for VBGT and oncolytic products during preclinical and clinical development and how shedding data can be used to assess the potential for transmission to untreated individuals. This guidance finalizes the draft guidance of the same title dated July 2014.
Prolonged SARS-CoV-2 RNA shedding and recurrence of PCR-positive tests have been widely reported in patients after recovery, yet these patients most commonly are non-infectious. Here we investigated the possibility that SARS-CoV-2 RNAs can be reverse-transcribed and integrated into the human genome and that transcription of the integrated sequences might account for PCR-positive tests. In support of this hypothesis, we found chimeric transcripts consisting of viral fused to cellular sequences in published data sets of SARS-CoV-2 infected cultured cells and primary cells of patients, consistent with the transcription of viral sequences integrated into the genome. To experimentally corroborate the possibility of viral retro-integration, we describe evidence that SARS-CoV-2 RNAs can be reverse transcribed in human cells by reverse transcriptase (RT) from LINE-1 elements or by HIV-1 RT, and that these DNA sequences can be integrated into the cell genome and subsequently be transcribed. Human endogenous LINE-1 expression was induced upon SARS-CoV-2 infection or by cytokine exposure in cultured cells, suggesting a molecular mechanism for SARS-CoV-2 retro-integration in patients. This novel feature of SARS-CoV-2 infection may explain why patients can continue to produce viral RNA after recovery and suggests a new aspect of RNA virus replication.
http://archive.today/2021.12.24-130415/https://pubmed.ncbi.nlm.nih.gov/33330870/