Transplant InternationalVolume 34, Issue 6 p. 1019-1031 ReviewOpen Access Early detection of SARS-CoV-2 and other infections in solid organ transplant recipients and household members using wearable devices Brendan J. Keating, Corresponding Author Brendan J. Keating [email protected] orcid.org/0000-0002-3320-3723 Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Correspondence Brendan J. Keating D.Phil, Division of Transplantation, Department of Surgery, University of Pennsylvania, Office 414A Stemmler Building, 3450 Hamilton Walk, Philadelphia PA, 19104, USA. Tel: +1 267-760-4507; fax: +1 215-662-2244; e-mail: [email protected]Search for more papers by this authorEyas H. Mukhtar, Eyas H. Mukhtar Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorEric D. Elftmann, Eric D. Elftmann Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorFeyisope R. Eweje, Feyisope R. Eweje Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorHui Gao, Hui Gao Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorLina I. Ibrahim, Lina I. Ibrahim Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorRanganath G. Kathawate, Ranganath G. Kathawate Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorAlexander C. Lee, Alexander C. Lee Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorEric H. Li, Eric H. Li Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorKrista A. Moore, Krista A. Moore Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorNikhil Nair, Nikhil Nair Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorVenkata Chaluvadi, Venkata Chaluvadi Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorJanaiya Reason, Janaiya Reason Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorFrancesca Zanoni, Francesca Zanoni Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Division of Nephrology, Department of Medicine, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, USASearch for more papers by this authorAlexander T. Honkala, Alexander T. Honkala Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAmein K. Al-Ali, Amein K. Al-Ali Department of Clinical Biochemistry, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi ArabiaSearch for more papers by this authorFatima Abdullah Alrubaish, Fatima Abdullah Alrubaish Department of Internal Medicine, King Fahd Hospital of The University, Imam Abdulrahman Bin Faisal University, Alkhobar, Saudi ArabiaSearch for more papers by this authorMaha Ahmad Al-Mozaini, Maha Ahmad Al-Mozaini Immunocompromised Host Research, Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi ArabiaSearch for more papers by this authorFahad A. Al-Muhanna, Fahad A. Al-Muhanna Department of Internal Medicine, King Fahd Hospital of The University, Imam Abdulrahman Bin Faisal University, Alkhobar, Saudi ArabiaSearch for more papers by this authorKhaldoun Al-Romaih, Khaldoun Al-Romaih National Centre of Genomic Technology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi ArabiaSearch for more papers by this authorSamuel B. Goldfarb, Samuel B. Goldfarb Division of Pulmonary Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorRyan Kellogg, Ryan Kellogg Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorKrzysztof Kiryluk, Krzysztof Kiryluk Division of Nephrology, Department of Medicine, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, USASearch for more papers by this authorSarah J. Kizilbash, Sarah J. Kizilbash Department of Pediatrics, University of Minnesota, Minneapolis, MN, USASearch for more papers by this authorTaisa J. Kohut, Taisa J. Kohut Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorJuhi Kumar, Juhi Kumar Weill Cornell Medical College, New York, NY, USASearch for more papers by this authorMatthew J. O'Connor, Matthew J. O'Connor Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorElizabeth B. Rand, Elizabeth B. Rand Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorRobert R. Redfield, Robert R. Redfield Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorBenjamin Rolnik, Benjamin Rolnik Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorJoseph Rossano, Joseph Rossano Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorPablo G. Sanchez, Pablo G. Sanchez Division of Lung Transplant and Lung Failure, Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USASearch for more papers by this authorArash Alavi, Arash Alavi Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAmir Bahmani, Amir Bahmani Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorGireesh K. Bogu, Gireesh K. Bogu Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAndrew W. Brooks, Andrew W. Brooks Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAhmed A Metwally, Ahmed A Metwally Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorTejas Mishra, Tejas Mishra Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorStephen D. Marks, Stephen D. Marks Great Ormond Street Hospital for Children, NHS Foundation Trust London, London, UK NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health, London, UKSearch for more papers by this authorRobert A. Montgomery, Robert A. Montgomery New York University Langone Transplant Institute, New York, NY, USASearch for more papers by this authorJay A. Fishman, Jay A. Fishman Transplant Infectious Disease Program, Infectious Disease Division, and Transplant Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USASearch for more papers by this authorSandra Amaral, Sandra Amaral Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorPamala A. Jacobson, Pamala A. Jacobson Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, MN, USASearch for more papers by this authorMeng Wang, Meng Wang Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorMichael P. Snyder, Michael P. Snyder Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this author Brendan J. Keating, Corresponding Author Brendan J. Keating [email protected] orcid.org/0000-0002-3320-3723 Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Correspondence Brendan J. Keating D.Phil, Division of Transplantation, Department of Surgery, University of Pennsylvania, Office 414A Stemmler Building, 3450 Hamilton Walk, Philadelphia PA, 19104, USA. Tel: +1 267-760-4507; fax: +1 215-662-2244; e-mail: [email protected]Search for more papers by this authorEyas H. Mukhtar, Eyas H. Mukhtar Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorEric D. Elftmann, Eric D. Elftmann Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorFeyisope R. Eweje, Feyisope R. Eweje Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorHui Gao, Hui Gao Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorLina I. Ibrahim, Lina I. Ibrahim Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorRanganath G. Kathawate, Ranganath G. Kathawate Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorAlexander C. Lee, Alexander C. Lee Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorEric H. Li, Eric H. Li Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorKrista A. Moore, Krista A. Moore Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorNikhil Nair, Nikhil Nair Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorVenkata Chaluvadi, Venkata Chaluvadi Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorJanaiya Reason, Janaiya Reason Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorFrancesca Zanoni, Francesca Zanoni Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Division of Nephrology, Department of Medicine, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, USASearch for more papers by this authorAlexander T. Honkala, Alexander T. Honkala Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAmein K. Al-Ali, Amein K. Al-Ali Department of Clinical Biochemistry, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi ArabiaSearch for more papers by this authorFatima Abdullah Alrubaish, Fatima Abdullah Alrubaish Department of Internal Medicine, King Fahd Hospital of The University, Imam Abdulrahman Bin Faisal University, Alkhobar, Saudi ArabiaSearch for more papers by this authorMaha Ahmad Al-Mozaini, Maha Ahmad Al-Mozaini Immunocompromised Host Research, Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi ArabiaSearch for more papers by this authorFahad A. Al-Muhanna, Fahad A. Al-Muhanna Department of Internal Medicine, King Fahd Hospital of The University, Imam Abdulrahman Bin Faisal University, Alkhobar, Saudi ArabiaSearch for more papers by this authorKhaldoun Al-Romaih, Khaldoun Al-Romaih National Centre of Genomic Technology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi ArabiaSearch for more papers by this authorSamuel B. Goldfarb, Samuel B. Goldfarb Division of Pulmonary Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorRyan Kellogg, Ryan Kellogg Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorKrzysztof Kiryluk, Krzysztof Kiryluk Division of Nephrology, Department of Medicine, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, USASearch for more papers by this authorSarah J. Kizilbash, Sarah J. Kizilbash Department of Pediatrics, University of Minnesota, Minneapolis, MN, USASearch for more papers by this authorTaisa J. Kohut, Taisa J. Kohut Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorJuhi Kumar, Juhi Kumar Weill Cornell Medical College, New York, NY, USASearch for more papers by this authorMatthew J. O'Connor, Matthew J. O'Connor Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorElizabeth B. Rand, Elizabeth B. Rand Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorRobert R. Redfield, Robert R. Redfield Division of Transplantation, Department of Surgery, Penn Transplant Institute, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USASearch for more papers by this authorBenjamin Rolnik, Benjamin Rolnik Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorJoseph Rossano, Joseph Rossano Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorPablo G. Sanchez, Pablo G. Sanchez Division of Lung Transplant and Lung Failure, Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USASearch for more papers by this authorArash Alavi, Arash Alavi Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAmir Bahmani, Amir Bahmani Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorGireesh K. Bogu, Gireesh K. Bogu Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAndrew W. Brooks, Andrew W. Brooks Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorAhmed A Metwally, Ahmed A Metwally Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorTejas Mishra, Tejas Mishra Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorStephen D. Marks, Stephen D. Marks Great Ormond Street Hospital for Children, NHS Foundation Trust London, London, UK NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health, London, UKSearch for more papers by this authorRobert A. Montgomery, Robert A. Montgomery New York University Langone Transplant Institute, New York, NY, USASearch for more papers by this authorJay A. Fishman, Jay A. Fishman Transplant Infectious Disease Program, Infectious Disease Division, and Transplant Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USASearch for more papers by this authorSandra Amaral, Sandra Amaral Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USASearch for more papers by this authorPamala A. Jacobson, Pamala A. Jacobson Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, MN, USASearch for more papers by this authorMeng Wang, Meng Wang Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this authorMichael P. Snyder, Michael P. Snyder Department of Genetics, Stanford University School of Medicine, Stanford, CA, USASearch for more papers by this author First published: 18 March 2021 https://doi.org/10.1111/tri.13860AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Summary The increasing global prevalence of SARS-CoV-2 and the resulting COVID-19 disease pandemic pose significant concerns for clinical management of solid organ transplant recipients (SOTR). Wearable devices that can measure physiologic changes in biometrics including heart rate, heart rate variability, body temperature, respiratory, activity (such as steps taken per day) and sleep patterns, and blood oxygen saturation show utility for the early detection of infection before clinical presentation of symptoms. Recent algorithms developed using preliminary wearable datasets show that SARS-CoV-2 is detectable before clinical symptoms in >80% of adults. Early detection of SARS-CoV-2, influenza, and other pathogens in SOTR, and their household members, could facilitate early interventions such as self-isolation and early clinical management of relevant infection(s). Ongoing studies testing the utility of wearable devices such as smartwatches for early detection of SARS-CoV-2 and other infections in the general population are reviewed here, along with the practical challenges to implementing these processes at scale in pediatric and adult SOTR, and their household members. The resources and logistics, including transplant-specific analyses pipelines to account for confounders such as polypharmacy and comorbidities, required in studies of pediatric and adult SOTR for the robust early detection of SARS-CoV-2, and other infections are also reviewed. Introduction Post-transplant infectious disease complications are a leading cause of mortality in solid organ transplant recipients (SOTR) [1, 2. In particular, complications of respiratory infections have been shown to have devastating consequences in SOTR, with earlier diagnosis and treatment resulting in better outcomes [3. Recent prospective multicenter studies in adult SOTR with clinically managed influenza infection showed ~66–71% of recipients required hospitalization with >30% developing pneumonia and 11–16% requiring intensive care unit (ICU) admission with mortality rates of 4–4.6% [4, 5. Notably, SOTR who received antiviral treatment within 48 hours of influenza A (H1N1) symptom presentation showed decreased rates of ICU admission (8%) compared to those who received treatment after 48 h (22%) as well as decreased incidence of hospital admission and mechanical ventilation [4. The recent COVID-19 pandemic presents increased risk of severe SARS-CoV-2 infection in the immunosuppressed SOTR. Literature reviews show 16–28% COVID-related mortality rates in SOTR [6-8, although larger studies are needed to dissect known comorbidity/risk factors. The mean incubation period of SARS-CoV-2 reported in large studies varies from 5.7 days (95% CI, 5.1–6.4) to 7.7 days (95% CI 7.02–8.53) [9, 10. This period is longer than the median incubation periods for other common respiratory viral infections: influenza B = 0.6 days (95% CI 0.5–0.6); influenza A = 1.4 days (95% CI 1.3–1.5); rhinovirus = 1.9 days (95% CI 1.4–2.4); parainfluenza = 2.6 days (95% CI 2·1–3·1), SARS-CoV-1 = 4.0 days (95% CI 3·6–4·4); respiratory syncytial virus (RSV) = 4.4 days (95% CI 3.9–4.9) and adenovirus = 5.6 days (95% CI 4·8–6·3) [11. Furthermore, a number of recent studies have shown prolonged viral shedding, and meta-analyses show that SOTRs have higher viral burdens of SARS-CoV-2 [12-14 Importantly, a number of studies have estimated that up to 50% of individuals infected with SAR-CoV-2 have asymptomatic infection courses, which significantly increases the risk of viral spread in a household or care center [15, 16. The mean serial interval, a key parameter for assessing the dynamics of a disease, has been shown to range from 3.03 to 7.6 days for SAR-CoV-2 between the initial infectious person and the person they infect, indicating that there is ample time for transmission of SARS-CoV-2 within a household, or care facility, while individuals are in pre-symptomatic or asymptomatic phases of infection [17. Sequencing of airway microbiota in pneumonia patients with COVID-19 (n = 62) and without COVID-19 (n = 125) showed COVID-19 patients had more perturbed airway microbiota with identification of other potential pathogen in 47% of cases, of which 58% were respiratory viruses. In nasopharyngeal and sputum samples from COVID-19 patients, enrichment of other putative pathogenic microbes was identified, including respiratory syncytial viruses (RSV), influenza, and other opportunistic pathogen [18. Therefore, early detection of infection and early therapeutic intervention with promising corticosteroid and antibody-based regimens may be essential to mitigating the consequences of severe COVID-19 infection in SOTR. As of January 20th, 2021, over 291 million SARS-CoV-2 viral tests were performed in the United States and ~1.361 billion worldwide [19. With an asymptomatic incubation period up to ~14 days and wide heterogeneity in clinical symptoms, early detection of SARS-CoV-2 is imperative, yet there remain major barriers to widespread and continuous testing. Most existing testing platforms are not practical to administer on a daily/weekly basis due to transmission risks and significant logistical barriers. Furthermore, the results of diagnostic tests can take several days restricting the window for early intervention, contact tracing, and impeding data-driven healthcare decisions for high-risk individuals [20. Finally, there is understandable reluctance from SOTR and their families to enter healthcare settings for routine visits due to potential nosocomial SARS-CoV-2 exposure. The lengthy asymptomatic incubation period of SARS-CoV-2 and its remarkable transmissibility, combined with a presentation altered by immunosuppression, and polypharmacy among transplant populations, reflect the urgent need for tools that can detect pre-symptomatic infection. As SARS-CoV-2 sero-prevalence rises, more SOTR and family members will become infected, and many cases may not be detected early enough for effective intervention. Wearable devices In the last decade, advances in wearable devices such as fitness tracker smartwatches allow a range of important phenotypes to be measured and offer the potential to shift clinical care from being reactive to proactive. A study conducted in June 2019 showed that ~21% of the US population have, and regularly wear, a smartwatch55, and this trend appears to be increasing as they become more affordable. Generally, an increased heart rate (HR) of 10 beats per minute in children equates to an increase of one degree centigrade from their baseline temperature [21. While activity can impact HR short-term, prolonged periods of sustained HR increase over 12–36 hours may indicate a physiological reaction to infection. With the ability to monitor physiological parameters such as HR, body temperature, oxygen saturation (SpO2), blood pressure (BP), sleep and respiratory patterns, and electro-dermal activity, commercially available wearables provide the opportunity for real-time, continuous infection monitoring to complement conventional diagnostic tests. There are many commercially available wrist watches that utilize photoplethysmography (PPG) sensors which shine light into the skin and measure the reflection back to determine blood flow and color (green light is absorbed by hemoglobin). These blood flow measurements are used to determine HR, and to estimate BP and SpO2 [22. Inflatable wrist-cuffs can measure arterial pressure to find Oscillometric BP and some wearable devices use single-lead electrocardiography (ECG) to detect heart rhythm, for example, Apple Watch. Over the past few years, wearable devices have been rigorously explored for the detection and/or monitoring of pathologies across a range of diseases, including atrial fibrillation, Parkinson's disease, convulsive seizure onset, and continuous glucose monitoring in individuals with type 2 Diabetes [23-26. A growing number of studies have shown that wearable devices are also a powerful and promising tool for infection detection. While wearable technologies have yet to be extensively used for monitoring of SOTRs, a study of 88 Australian adult CKD and kidney transplant recipients, a clinical-grade wearable device measuring peripheral body temperature with an infrared thermopile correctly identified infection in 65 patients with 80% sensitivity and 98% specificity [27. Another study found that Bluetooth-enabled devices for at-home physiological monitoring of lung transplant recipients resulted in lower incidences of hospital readmissions [28. The at-home monitoring consisted of daily updates of BP, HR, weight, blood glucose, SpO2, pulmonary function, and activity levels, which could be measured using wearable devices. The rate of hospital readmission and readmission days with home monitoring versus standard care was 56% and 46% respectively, demonstrating the potential value of consistently monitoring SOTRs with wearable devices to reduce hospitalizations. One of the first studies to report using wearables to detect SARS-CoV-2 infection via smartwatches was published recently by a number of co-authors of this manuscript. Using primarily retrospective data from ~5,300 wearable devices, a focus was placed on individuals wearing similar devices where sufficient continuous and robust measurements were available [29. The algorithms studied three parameters: increased resting HR (RHR) relative to previous "healthy day" windows; increased HR to activity (step count) ratio; and sleep measures including sleep duration and time in wake/light/deep/REM stages. Wearables data from 32 individuals pre-, peri-, and post-SARS-CoV-2 confirmed infection, identified aberrant physiological signals associated with illness using various algorithms including proof-of-concept for real-time disease detection. The study showed that it is possible to identify infection prior to symptomatic onset using just three parameters using consumer-grade wearable devices. A similar study demonstrated that combining symptom data (fatigue, breathing difficulty, fever, etc.) with wearable sensor data (resting HR, sleep, and activity) resulted in greater ability to discriminate between COVID-19 and non-COVID-19 infection compared to symptoms alone (AUC 0.80 vs. 0.71, P < 0.01) [30. The recent TemPredict study, using Oura wearable ring data from 65,000 subjects, examined 50 COVID-19 confirmed cases and showed the ability to detect early signs of fever in 93% of the cases on average 3 days before symptoms manifest
