UMMS Affiliation

Department of Population and Quantitative Health Sciences

Publication Date


Document Type

Article Preprint


Health Information Technology | Immunology and Infectious Disease | Infectious Disease | Translational Medical Research | Virus Diseases


Since late 2019, the novel coronavirus SARS-CoV-2 has introduced a wide array of health challenges globally. In addition to a complex acute presentation that can affect multiple organ systems, increasing evidence points to long-term sequelae being common and impactful. The worldwide scientific community is forging ahead to characterize a wide range of outcomes associated with SARS-CoV-2 infection; however the underlying assumptions in these studies have varied so widely that the resulting data are difficult to compare. Formal definitions are needed in order to design robust and consistent studies of Long COVID that consistently capture variation in long-term outcomes. Even the condition itself goes by three terms, most widely "Long COVID", but also "COVID-19 syndrome (PACS)" or, "post-acute sequelae of SARS-CoV-2 infection (PASC)". In the present study, we investigate the definitions used in the literature published to date and compare them against data available from electronic health records and patient-reported information collected via surveys. Long COVID holds the potential to produce a second public health crisis on the heels of the pandemic itself. Proactive efforts to identify the characteristics of this heterogeneous condition are imperative for a rigorous scientific effort to investigate and mitigate this threat.


COVID-19, Long COVID, COVID-19 syndrome (PACS), post-acute sequelae of SARS-CoV-2 infection (PASC), definitions, UMCCTS funding

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The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license.

DOI of Published Version



Rando HM, Bennett TD, Byrd JB, Bramante C, Callahan TJ, Chute CG, Davis HE, Deer R, Gagnier J, Koraishy FM, Liu F, McMurry JA, Moffitt RA, Pfaff ER, Reese JT, Relevo R, Robinson PN, Saltz JH, Solomonides A, Sule A, Topaloglu U, Haendel MA. Challenges in defining Long COVID: Striking differences across literature, Electronic Health Records, and patient-reported information. medRxiv [Preprint]. 2021 Mar 26:2021.03.20.21253896. doi: 10.1101/2021.03.20.21253896. PMID: 33791733; PMCID: PMC8010765. Link to preprint on publisher's site

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medRxiv : the preprint server for health sciences


This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.

Full author list omitted for brevity. For the full list of authors, see article.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.