First Comprehensive Review On How Covid-19 Affects Many Different Organs, Not Just Lungs

An artist's illustration of SARS-CoV-2, the pathogen responsible for Covid-19. NIAID

The more scientists are learning about Covid-19, the clearer it is that it's not just a “nasty cough” that affects the respiratory system. An increasing amount of evidence is showing that the novel coronavirus can affect a range of vital organs beyond the lungs, including kidneys, the heart, the gut, the brain, and more.

Back in April, doctors from Columbia University Irving Medical Center (CUIMC) in New York City, the epicenter of the US coronavirus outbreak at the time, started to notice many of their Covid-19 patients were displaying much more than simply respiratory symptoms. Built on their own experiences and dozens of medical reports from around the world, they have now released the first extensive review of Covid-19's effects on all affected organs outside the lungs.

Reported in the journal Nature Medicine, the team lay out all of the known information about how Covid-19 affects everything from the skin and brain to blood-forming organs and kidneys. 

"Physicians need to think of COVID-19 as a multisystem disease," Aakriti Gupta, lead author and cardiologist at CUIMC, said in a statement

"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, and physicians need to treat those conditions along with the respiratory disease."

Much of these complications are linked to inflammation and blood clots. The virus is also known to create an intense “runaway” response from the immune system. While the immune response is meant to help rid the body of the infection, it can effectively go into overdrive and leads to untempered inflammation. According to the researchers, clots are a prominent effect of the disease because of the way the virus attacks cells that line the blood vessels. Once a blood clot has formed, it can travel all around the body via the blood vessels and cause problems for other organs, most notably the heart where it can cause a cardiac arrest. 

Beyond blood clots, the virus also appears to directly affect the heart, although no one is certain about how exactly it does this.

"The mechanism of heart damage is currently unclear, as the virus has not been frequently isolated from the heart tissue in autopsy cases," added Gupta.

Another key feature of Covid-19 infection is damage to the kidneys. The research team says they saw renal failure in around half of the hospitalized Covid-19 patients, with 5-10 percent requiring dialysis, a procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. This is most likely to do with the ACE2 receptor, a molecular doorway used by the virus to gain entry into the cells that are found in high concentrations in the kidney. 

Neurological symptoms – such as headache, dizziness, fatigue, loss of smell, and even hallucinations – may occur in about a third of patients. Strokes are also known to occur in up to 6 percent of severe cases. Although the mechanism behind this is hazy, blood clots and inflammation are the main culprits.  

Fortunately, there was some (kind of) relieving news. The paper found that symptoms that affected the skin tend to be relatively mild and the gastrointestinal problems associated with Covid-19 appear to resolve themselves with little trouble. 

"This virus is unusual and it's hard not to take a step back and not be impressed by how many manifestations it has on the human body," said co-author Mahesh Madhavan, MD, also a cardiology fellow at CUIMC.

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