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MIT Technology Review

This is what we know so far about how covid-19 affects the rest of the body

Category:
Coronavirus

Covid-19 is primarily a respiratory infection that attacks the lungs, making it harder for patients to breathe and get enough oxygen to the rest of the body. Pneumonia and other respiratory conditions can quickly set in, eventually leading to death if the body cannot fight off the infection. But after over four months of cases, doctors are getting a more detailed look at some of the unexpected ways the virus hits the human body beyond the nasal cavity, throat, and lungs. Here are a few new things we’ve learned in recent weeks:

The blood. There’s mounting evidence the inflammation that arises from a covid-19 infection leads to blood clots that can do serious harm. One of the biggest examples is “happy hypoxia,” which doctors so far suspect is caused by blood clots in the lungs. Many other reports indicate that these clots can affect any number of organs, including the kidneys, blood vessels, intestines, liver, and even the brain. One study from the Netherlands found that up to 38% of critically ill patients suffered from complications related to blood clots. 

The brain. The most severe effect the virus might have on the brain is a stroke most probably caused by—you guessed it—blood clots in arteries leading to the brain. This is happening even in young patients. But the virus may also be causing some milder neurological symptoms—most notably a loss of taste and smell. One study found that 65% of those who tested positive for coronavirus reported that phenomenon. Some scientists think it might be a sign the virus can directly affect the nervous system. Other studies out of Wuhan and France have also found neurological symptoms to be prevalent among covid-19 patients.

The heart. Besides clot-related complications caused by blockages in blood vessels, covid-19 seems to exacerbate stress to the heart and wear down cardiac muscle through a lack of oxygen if the lungs are struggling, or as a result of inflammation. And some case studies also suggest the virus is able to infect and damage cardiac tissue directly. 

The kidneys. Studies from China and Italy early in the outbreak found that about 25 to 27% of hospitalized patients who died experienced injury to their kidneys. Covid-19 patients suffering from pneumonia often seem to experience kidney injury as well. Why this is happening isn’t clear, but the main suspects thus far are blood clots in the vessels leading to the kidneys, overactive inflammation in the body, a lack of oxygen, or a direct viral attack on the kidneys.  

The immune system. As previously reported, some covid-19 patients are hit by what’s called a cytokine storm: the body’s inflammatory response (meant to help clear out infected cells) goes into overdrive and starts attacking healthy tissue and organs, even after the infection has been resolved. There’s no hard data yet for how many covid-19 patients are affected, since cytokine storms often exacerbate other severe conditions caused by infection, but many patients who die are observed to have high blood levels of cytokines (which spur immune system activity). The best treatments for this are cytokine-inhibiting drugs. One study suggests early use blood thinners might be useful in tempering cytokine activation and preventing a storm from breaking out.