The SARS-CoV-2 virus causes COVID-19, which ranges from mild initial symptoms to severe multi-organ dysfunction. While some patients recover to their baseline states, others develop a long COVID, or post-acute sequelae of SARS-CoV-2 (PASC) consisting of symptoms persisting \>2-6 months post-infection. PASC symptoms include post-exertional malaise, fatigue, and heart palpitations as well as incident GI disorders, cognitive dysfunction, and arthritis. Based on prevalence/incidence studies, it is estimated that more than 30 million people in the US have ever developed PASC with 10-11% of patients or 11 million people continuing to feel symptoms to the present day10. SARS-CoV-2 vaccines are only \ 32% effective against infection at 4 months post-vaccination11, only 15% effective against the development of PASC12, and only 20% of American adults have received an updated booster as of December 202313. It is therefore imperative that the scientific community make progress in identifying underlying causes of PASC to develop effective treatments. This study will identify microbial metabolites associated with PASC-mediated gut dysbiosis and establish a tractable in vitro model to test T cell-gut epithelium dynamics to develop novel bio-therapeutics for multiple post-viral conditions. This case-control study will collect biospecimens (matched stool \& blood) samples from 400 people with and without long COVID (200 participants/group) to understand how COVID-induced dysbiosis impacts symptom severity, immune suppression, and gut barrier dysfunction both ex vivo and in vitro.