A comprehensive review of COVID-19's effect on organ systems outside the lungs

In the early days of the COVID-19 pandemic, the disease was characterized by many as a flu-like respiratory infection mainly affecting the lungs. Now, physicians recognize that the coronavirus can impact organs throughout the body. In a collaboration among physicians at Beth Israel Deaconess Medical Center (BIDMC) and Columbia University Irving Medical Center, researcher-clinicians have conducted an extensive review of the latest findings on COVID-19's effect on organ systems outside the lungs. Their review, published in Nature Medicine, also summarized proposed mechanisms behind these wide-ranging systemic effects and provided clinical guidance for physicians.

Scientists all over the world are working at an unprecedented rate towards understanding how this virus specifically hijacks biological mechanisms of the human body that are normally protective. We hope that our review will be a comprehensive resource for physicians, nurses and other health care workers caring for patients with COVID-19, and provide impetus to consideration of all organ systems involved while developing research priorities and therapeutic strategies."

Kartik Sehgal, MD, co-lead author, hematology/oncology fellow in the Cancer Center at BIDMC

Based on their own experiences caring for patients with COVID-19 as well as recent reports in the scientific literature, the team of clinicians -- co-led by Columbia cardiology fellows Aakriti Gupta, MD and Mahesh V. Madhavan, MD, and senior author Donald Landry, MD, PhD, chair of medicine at the Columbia University Irving Medical Center -- delineate the myriad fronts on which the coronavirus may attack the body.

Beyond the severe respiratory distress now associated with severe COVID-19, the virus also may increase patients' risk of heart attack, kidney failure and clotting disorders, the physicians report. Neurological symptoms, including headache, dizziness, fatigue, and loss of smell, may occur in about a third of patients. Patients with severe cases of COVID-19 are also at risk for strokes caused by blood clots and delirium. "Physicians need to think of COVID-19 as a multisystem disease," said Gupta. "There's a lot of news about clotting but it's also important to understand that a substantial proportion of these patients suffer kidney, heart, and brain damage."

Scientists suspect these various complications may all stem from the systemic inflammation that can occur as the immune system attempts to fight off the virus's attack on the body, especially cells that line the blood vessels. When the virus attacks blood vessel cells, inflammation increases, and blood begins to form clots, big and small. These blood clots can travel all over the body and wreak havoc on organs, perpetuating a vicious cycle. In addition, the downstream messenger signals of the immune system may spiral out of control in severe cases, contributing to these widespread effects.

"Future studies following patients who experienced complications during hospitalizations for COVID-19 will be crucial," said Madhavan. "It really was quite astounding to see the significant ramifications this virus had on these other systems."

Breaking this cycle may be a promising way to treat patients with severe cases of COVID-19. A recent clinical trial has found that at a drug called dexamethasone -- a steroid the globally suppresses the immune system -- reduced deaths in ventilated patients by one-third.

"It's a relatively new virus and we're still learning about its long-term effects," said Sehgal. "The recognition of multi-system involvement by COVID-19 is important for optimal care of these patients while hospitalized, and to develop a comprehensive post-hospital discharge follow up plan."