The symptoms of COVID-19 may very well be eldritch horrors. In most cases, it can appear as cough, fever, chills and headache. But in severe cases, it can cause acute kidney failure and multiple organ damage – strange symptoms for what’s known as mainly a respiratory infection.
How COVID-19 causes the latter, in particular, was the focus of a recent paper by a team from University Hospital Zurich. In their report, senior author Frank Ruschitzka examined COVID-19 patients who exhibited severe symptoms. After the first body was autopsied, it showed tiny clots and dead cells within the capillaries of the lungs, as well as distended blood vessels in every organ in the body – a sign of severe inflammation.
This also showed why patients with severe COVID-19 are more likely to have strokes, blood clots and even heart attacks: The virus had targeted their blood vessels.
“[COVID-19] is a vascular problem,” added Ruschitzka, who published his team’s findings in the Lancet. “The lung is the main battlefield, but it’s a disease of the blood vessels.”
A blood vessel disease?
Months into the pandemic and with over 8 million cases and counting, medical experts are now looking into the possibility that COVID-19 is a vascular disease.
According to a study in the New England Journal of Medicine, patients who died from COVID-19 had nine times as many clots in their lungs as those who died of the H1N1 flu. Other studies have similar results, from inflammatory symptoms in children to strokes in adults with no history of the condition.
A study from Belgium looked at the findings of this study, as well as the Zurich study, and found that damage in the endothelial cells that line blood vessels in the lungs can predict if a COVID-19 patient will slip into the fatal “second phase” of the disease. In the report, senior author Peter Carmeliet explained that an infection can cause blood vessels to leak and clot in some patients. This, in turn, triggers inflammation in the body, as well as gives rise to acute respiratory distress syndrome (ARDS) – the complication responsible for most COVID-19 deaths.
“It’s a vicious cycle,” explained Nilam Mangalmurti, a lung expert at the Hospital of the University of Pennsylvania, who wasn’t involved in the new study.
Blood vessels link chronic disease and COVID-19
The Belgian study, published in Nature Reviews Immunology, can shine a light on why COVID-19 is life-threatening for people with chronic illnesses like diabetes, obesity and cardiovascular disease, as the cells lining their blood vessels are already compromised.
Endothelial cells do more than line blood vessels and tissues. They also control the flow of substances and fluid into and out of a tissue, regulate blood pressure, prevent inflammation and inhibit clots. When these are injured, the cells signal immune cells and clotting factors to help repair the site of injury, as well as warn other cells of potential invaders.
Based on autopsy reports detailed in the Zurich study, researchers of the Belgian study believe that SARS-CoV-2, the pathogen behind COVID-19, can cause this response to go out of control. (Related: Coronavirus hijacks immune cells to create cytokine storms, says new study.)
Aside from exploring the possibility of COVID-19 being a vascular disease, researchers are also looking into the idea of using existing anti-inflammatory and anti-clotting treatments for the disease. In the U.S. and Europe, clinical trials that use drugs are already in progress. In China, the government has taken a more natural route, promoting the benefits of traditional Chinese medicine in treating COVID-19.
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