Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, our group has initiated and engaged in a range of clinical research studies investigating the presentation, risk factors, natural history, prognostication, and outcomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with particular focus on the manifestations in and impact on the digestive tract.  This page summarizes the published studies to-date, with link to the articles on the official journal sites.

For inquiry regarding any of our published and ongoing COVID-19 research, please visit the Contact page for contact information.

For information regarding all our publications and other research work, please visit the Publications and the Reseach pages.


Gastrointestinal Manifestations of COVID-19

Although anecdotally COVID-19 presents most commonly with respiratory symptoms, SARS-CoV-2 obtains cellular entry via the widely expressed angiotensin-converting enzyme 2 (ACE2) receptors, thus increasing the risk of not only respiratory but also alimentary tract involvement. The prevalence and characteristics of gastrointestinal symptoms were analyzed in a multicenter cohort of COVID-19 patients in the United States.  Overall, approximately two thirds of patients with COVID-19 reported at least 1 gastrointestinal symptom, with loss of appetite and diarrhea being the most common.  Gastrointestinal symptoms were the predominant presenting complaint among one-fifth of patients and the initial presenting symptoms of COVID-19 among one-sixth of individuals.  Additionally, the cardinal COVID-19 symptoms of anosmia (loss of smell) and ageusia (loss of taste) were independently associated with nausea and anorexia at presentation. 


  • Redd WD, Zhou JC, Hathorn KE, McCarty TR, Bazarbashi AN, Thompson CC, Shen L, Chan WW. Prevalence and Characteristics of Gastrointestinal Symptoms in Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Infection in the United States: A Multicenter Cohort Study. Gastroenterology. 2020 08; 159(2):765-767.e2. PMID: 32333911.  Full text link:



Impact of Liver Disease and COVID-19

The impact of underlying chronic liver disease on the severity and outcomes of COVID-19 was assessed both in a multi-hospital healthcare system in Massachusetts and in a national multi-center study.  Chronic liver disease, particularly non-alcoholic fatty liver disease, independently correlated with the need for intensive care unit admission, mechanical ventilation, and death.


  • Hashemi N, Viveiros K, Redd WD, Zhou JC, McCarty TR, Bazarbashi AN, Hathorn KE, Wong D, Njie C, Shen L, Chan WW. Impact of chronic liver disease on outcomes of hospitalized patients with COVID-19: A multicentre United States experience. Liver Int. 2020 10; 40(10):2515-2521. PMID: 32585065. Full text link:
  • Kim D, Adeniji N, Latt N, Kumar S, Bloom PP, Aby ES, Perumalswami P, Roytman M, Li M, Vogel AS, Catana AM, Wegermann K, Carr RM, Aloman C, Chen V, Rabiee A, Sadowski B, Nguyen V, Dunn W, Chavin K, Zhou K, Lizaola-Mayo B, Moghe A, Debes J, Lee TH, Branch A, Viveiros K, Chan W, Chascsa D, Kwo P, Dhanasekaran R. Predictors of Outcomes of COVID-19 in Patients with Chronic Liver Disease: US Multi-center Study. Clin Gastroenterol Hepatol. 2020 Sep 17. PMID: 32950749. Full text link:


Pancreas and COVID-19

The clinical characteristics and significance of abnormal pancreatic enzymes among hospitalized patients with COVID-19 was assessed.  Mild elevation in serum lipase was observed in some patients hospitalized with COVID-19, however, clinical acute pancreatitis was not seen.  Hyperlipasemia alone was not associated with more severe disease or poor outcome.


  • McNabb-Baltar J, Jin DX, Grover AS, Redd WD, Zhou JC, Hathorn KE, McCarty TR, Bazarbashi AN, Shen L, Chan WW. Lipase Elevation in Patients With COVID-19. Am J Gastroenterol. 2020 08; 115(8):1286-1288. PMID: 32496339. Full text link:


Inflammatory Bowel Disease and COVID-19

The risk of COVID-19 infection among inflammatory bowel disease patients treated with systematic immunosuppressive therapy was evaluated in a multi-institutional cohort. Among 5302 IBD patients, 0.7% developed COVID-19, with no significant differences between those treated with immunosuppression and those who were not, even after adjusting for potential confounders and comorbidities. Immunosuppressive therapy was also not associated with more severe COVID-19 infection.  In a separate study, we found that a majority of IBD patients with COVID-19 may have prolonged positive SARS-CoV-2 PCR after symptoms resolve. IBD care, including resumption of immunosuppression, should not be delayed.


  • Burke KE, Kochar B, Allegretti JR, Winter RW, Lochhead P, Khalili H, Colizzo FP, Hamilton MJ, Chan WW, Ananthakrishnan AN. Immunosuppressive Therapy and Risk of COVID-19 Infection in Patients With Inflammatory Bowel Diseases. Inflamm Bowel Dis. 2020 Oct 22. PMID: 33089863. Full text link:
  • Winter RW, Ananthakrishnan AN, Burke KE, Kochar B, Chan WW, Allegretti JR. Time to Negative SARS-CoV-2 PCR Should Not Delay Care Among Patients With Inflammatory Bowel Diseases. Inflamm Bowel Dis. 2021 Feb 11. PMID: 33570095. Full text link:


Proton Pump Inhibitor Use and COVID-19

The relationship between proton pump inhibitor (PPI) exposure and clinical outcomes of hospitalized COVID-19 patients was assessed, as PPI was previously linked to increased hospital-acquired and ventilator-associated pneumonias. After controlling for potential confounders, PPI use among hospitalized COVID-19 patients was independently associated with greater need for mechanical ventilation and increased in-hospital mortality. Whether this indicates a causal relationship, or whether PPI use represents underlying GERD or other comorbidities with prognostic implications requires further investigations.


  • Wong D, Bazarbashi AN, Hathorn KE, McCarty TR, Redd WD, Zhou JC, Nije C, Lo WK, Shen L, Chan WW. Association Between Proton Pump Inhibitor Use and COVID-19 Related Hospitalization Outcomes. Am J Gastroenterol. 2020 10; 115:S689. Full text link:  


Cancer and COVID-19 Gastrointestinal Manifestations

The gastrointestinal manifestations of COVID-19 among patients with active malignancy was characterized. Among oncology patients hospitalized with COVID-19, 63% reported at least one new gastrointestinal symptoms, with anorexia, diarrhea, and vomiting being the most common and 17% describing severe symptoms.  In addition, elevated liver enzymes were found in 33% of patients at the time of presentation. Patients with elevated liver enzymes were more likely to experience gastrointestinal symptoms.  


  • Grover S, Redd WD, Zhou JC, Nije C, Wong D, Hathorn KE, McCarty TR, Bazarbashi AN, Shen L, Chan WW. High Prevalence of Gastrointestinal Manifestations of COVID-19 Infection in Hospitalized Patients With Cancer. J Clin Gastroenterol. 2020 Oct 27. PMID: 33116066. Full text link:


Clostridioides difficile Infection in COVID-19 Patients

The prevalence and outcome of Clostridioides difficile infection (CDI) among hospitalized COVID-19 patients were evaluated, given the frequent use of broad-spectrum antibiotics and the high prevalence of gastrointestinal symptoms among these patients. Despite high antibiotics use, COVID-19 patients did not have higher overall CDI positive rate compared to historic controls pre-pandemic. However, among hospitalized COVID-19 patients who developed CDI, the all-cause in-hospital mortality was significantly increased.  


  • Allegretti JR, Nije C, McClure E, Redd WD, Wong D, Zhou JC, Bazarbashi AN, McCarty TR, Hathorn KE, Shen L, Jajoo K, Chan WW. Clostridioides difficile Infection in COVID-19 Patients. JGH Open. 2021 March. Full text link:  


Clinical Outcome Prediction

COVID-AID score (on-line calculator)

A prediction model for short-term mortality among hospitalized COVID-19 patients derived and validated using cohorts from Weill Cornell Medicine and Brigham and Women's Hospital.  This simple, easy-to-use prediction model utilizes 4 clinical parameters routinely obtained on presentation: age, blood pressure, presence of severe hypoxemia, and serum creatinine level.


  • Hajifathalian K, Sharaiha RZ, Kumar S, Krisko T, Skaf D, Ang B, Redd WD, Zhou JC, Hathorn KE, McCarty TR, Bazarbashi AN, Njie C, Wong D, Shen L, Sholle E, Cohen DE, Brown RS Jr, Chan WW, Fortune BE. Development and external validation of a prediction risk model for short-term mortality among hospitalized U.S. COVID-19 patients: A proposal for the COVID-AID risk tool. PLoS One. 2020 Sep 30;15(9):e0239536. doi: 10.1371/journal.pone.0239536. PMID: 32997700. Full text link:


Race/Ethnicity and COVID-19 Outcome

The clincal presentation and outcome were compared among racial/ethnic groups in hospitalized COVID-19 patients at the largest multi-hospital health system in Massachusetts.  After controlling for key demographic/clinical characteristics, there was no association between race/ethnicity and clinically relevant hospitalization outcomes, including in-hospital mortality. While COVID-19 had been shown in population-based studies to disproportionately affect racial/ethnic minorities, our findings serve to refute suggestions that certain races/ethnicities may be biologically predisposed to poorer COVID-19 outcomes. 


  • McCarty TR, Hathorn KE, Redd WD, Rodriguez NJ, Zhou JC, Bazarbashi AN, Njie C, Wong D, Trinh QD, Shen L, Stone VE, Chan WW. How Do Presenting Symptoms and Outcomes Differ by Race/Ethnicity Among Hospitalized Patients with COVID-19 Infection? Experience in Massachusetts. Clin Infect Dis. 2020 Aug 22. PMID: 32827436. Full text link: