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. Author manuscript; available in PMC: 2025 Apr 6.
Published in final edited form as: Nat Med. 2020 Jul 10;26(7):1017–1032. doi: 10.1038/s41591-020-0968-3

Table 1 |.

Future directions for research pertaining to various organ systems affected by COVID-19

General

Pathophysiological Clinical

• How long does infectious SARS-CoV-2 persist in the upper airway of an infected patient?
• How does SARS-CoV-2 disseminate in extrapulmonary tissues? Is hematogenous spread of the virus required for the direct cytotoxic effects to occur?
• Do other organs serve as sites of viral infection and persistence?
• Is extrapulmonary involvement dependent on viral load?
• Is extrapulmonary involvement dependent on mutations of SARS-CoV-2 or ACE2 polymorphisms?
• What role do host factors such as genetics (Toll-like receptors or complement components) or post-transcriptional modifications have in extrapulmonary SARS-CoV-2 infection? Are there biologically relevant factors (in addition to social factors) that explain the observed race disparities in incidence and outcomes?
• What is the predominant mechanism underlying the multiple organ dysfunction; is it direct virus-induced tissue damage, systemic cytokine-release syndrome, or the synergistic effects of both? What is the role of other proposed mechanisms such as RAAS dysregulation and endothelialitis?
• What is the impact of COVID-19 on the capacity to care for competing patients without COVID-19?
• What is the efficacy, safety, and proper timing for the use of antiviral and anti-inflammatory therapies currently under investigation?
• How should these therapies be best used in conjunction with each other to maximize efficacy while considering safety profiles?
• Is there a role for recombinant ACE2 in treatment of patients with COVID-19?

Hematologic

Pathophysiological Clinical
• What are the mechanisms of viral entry into lymphocytes?
• Does SARS-CoV-2 exert direct effects on coagulation and complement pathways, and if so, which ones?
• In addition to IL-6, which cytokines and chemokines may act as therapeutic targets for COVID-19?
• How is interferon signaling modulated by SARS-CoV-2? Are there differences in interferon responses in the early stages versus the late stages of COVID-19?
• Do novel measurements of hypercoagulability offer improved assessment of thrombotic risk?
• Is there a role for empiric higher-intensity (prophylactic or therapeutic dose) anticoagulation in patients who do not have documented thromboembolic events?
• Does post-hospitalization extended thromboprophylaxis improve patient outcomes?
• Does targeting inflammatory pathways and cytokine storm result in a reduction in the rate of thrombotic complications in COVID-19?
• Which patients, if any, would benefit from empiric thrombolytic therapy?

Cardiovascular

Pathophysiological Clinical
• Does direct cardiac viral toxicity contribute substantially to myocardial dysfunction?
• Are the mechanisms that result in myocardial injury and MI substantially different from those that are observed with other viral and bacterial infections?
• What are the mechanisms of cardiac arrhythmias in patients with COVID-19?
• What is the optimal antithrombotic regimen (including antiplatelets and anticoagulants) in patients presenting with COVID-19 with evidence of myocardial injury or MI?
• Do statins have a protective role in patients with COVID-19, given the ability of statins to downregulate ACE2, as well as their anti-inflammatory and other pleiotropic effects?
• Among the patients who develop right ventricular dysfunction in COVID-19, what proportion have pulmonary embolism and what proportion are due to the development of pulmonary hypertension or isolated right ventricular failure due to other causes?
• What strategies should be used to assess and treat acute right ventricular dysfunction in patients with COVID-19 without pulmonary embolism? Can this dysfunction be temporized with mechanical circulatory support or pulmonary vasodilators?

Renal

Pathophysiological Clinical
• How does SARS-COV-2 induce renal tubular injury?
• What is the mechanism of the development of electrolyte abnormalities and proteinuria in patients with COVID-19?
• Does SARS-CoV-2 act as a 'second hit' that potentiates the glomerular damage attributed to APOL1 risk genotypes, as seen with development of collapsing-variant focal segmental glomerulosclerosis in some cases?
• What is the optimal volume-management strategy in patients with COVID-19 who are at high risk of AKI, while also at risk of ARDS and myocardial injury?
• What is the frequency of renal recovery in patients who develop renal failure?
• Is there a role for cytokine removal through hemofiltration in patients with severe COVID-19?

Gastrointestinal and hepatobiliary

Pathophysiological Clinical
• What is the duration and extent of fecal shedding of SARS-CoV-2?
• Does fecal shedding have a role in viral transmission?
• What is the role of intestinal entry by the virus? Can the microbiome alter susceptibility to SARS-CoV-2 infection?
• What are the predominant mechanisms of hepatocellular damage in COVID-19?
• Do the hematologic abnormalities associated with COVID-19 increase the likelihood of developing gastrointestinal bleeding? How can this risk be best balanced with the risk for coagulopathy and thrombotic complications?
• Do antihistaminic agents (e.g., famotidine) have a role in prophylaxis against gastrointestinal pathology, including bleeding events? Do these agents have antiviral efficacy against SARS-CoV-2?

Endocrinologic

Pathophysiological Clinical
• Is the COVID-19-induced metabolic disarray a direct consequence of viral action?
• Does SARS-CoV-2 cause metabolic disarray by indirect effects such as altered nutrient utilization, cytokines and inflammation, and counter-regulatory hormones?
• Is ACE2 expressed uniformly in pancreatic β-cells and endocrine islets?
• If there is evidence of direct viral damage in pancreas, what is the nature of islet damage?
• Is there evidence of impairment of insulin action in patients with COVID-19?
• Do metabolic differences contribute to the racial disparities seen with COVID-19?
• Do the anti-inflammatory properties of agents used to treat diabetes mellitus or metabolic syndrome (e.g., metformin) have a protective effect in patients with COVID-19 and stable renal function?

Neurologic

Pathophysiological Clinical
• Does SARS-CoV-2 directly infect neurons, and if so, which neuron types?
• Does SARS-CoV-2 have a tropism for the brainstem and its medullary respiratory centers, and does this contribute to respiratory failure?
• Do the neurologic and neuroimaging features of stroke differ in patients with COVID-19?
• Are there long-term neurological complications in people who recover from SARS-CoV-2 infection?