Covid-19 is not a vascular disease

You have sent us an article published in the media that talks about a study from San Diego University which supposedly affirms that “covid-19 is not a respiratory but a vascular disease”. This is FALSE. As the World Health Organisation has explained, most of the infections affect the respiratory system, although they can also have implications in other organs. The study cited by the article does not deny such a thing, but rather deepens into how SARS-CoV2 affects the circulatory system.

"A study by the University of San Diego provides proof that COVID-19 is not a respiratory but a vascular disease. This could explain the presence of blood thrombi -perhaps also those following inoculation with certain vaccines- and other symptoms such as “COVID feet” which did not seem to have room in a classical respiratory disease"

The inaccuracy comes from a divulgative article published by the Salk Institute (California, US), which echoes from a study published in Circulation Research, a journal edited by the American Heart Association (AHA), of which they have been a part. In this text, it is stated that the study confirms covid-19 "as a primarily vascular disease". This newspaper has tried to contact both the Institute's communications department and the project leader to clarify whether this is an inaccuracy or if this is really what the trial suggests, but has not yet received a response.

If we look at the paper, what it says is that this group of researchers from the University of San Diego California, along with others from Salk, Jiaotong University and the University Health Science Center (the latter two located in Xi'an, China) have discovered a new way in which SARS-CoV-2 attacks the cells of the cardiovascular system. From this, Salk draws the above-mentioned conclusions, but the study does not say exactly that.

What has been discovered?

Covid-19 is is an infectious respiratory disease that can manifest itself in multiple ways, but in most people it causes mild to moderate respiratory symptoms, according to organisations such as the Spanish Ministry of Health and the US Centers for Disease Control and Prevention. In addition to affecting the respiratory system, the coronavirus has implications for other systems, including the cardiovascular one. This has been detected before. What the paper in question provides are details of how it reaches the blood vessels.

According to the researchers, the protein s or spike present in SARS-CoV-2 indirectly damages the cells of the endothelium, the monolayer that separates the tissues from the blood: "What is indicated in the journal is that there is endothelial involvement within the (blood) vessels, especially in the smaller ones," Ángel Cequier, a member of the Cardiology Service of the University Hospital of Bellvitge (Barcelona), and president of the Spanish Society of Cardiology (SEC, in Spanish), told Verificat. In other words, this is "additional, concomitant, non-exclusive data", that is, it is not intended to convey the idea that covid-19 is a vascular disease, but rather to emphasise "the very systemic and multi-organ involvement that covid-19 produces", he concludes. 

A different view

All this is, in fact, what researchers themselves point out in the first paragraph of the study: “Protein S alone can only damage vascular endothelial cells by down-regulating ACE2 (a protein responsible for controlling blood pressure) and thereby inhibiting mitochondrial function". Yet the study has important limitations, including that it was conducted in mice, and that they did not actually use the real SARS-CoV-2, but a similar non-infectious pseudovirus. 

Therefore, the contribution of the researchers from the University of San Diego California is rather a different look at how SARS-CoV-2 reaches virtually every corner of the body and, in particular, the blood vessels: "In the paper they highlight how the vessels are disrupted, endothelial dysfunction is documented, but this does not give it an aetiological exclusivity (this is not solely the cause of the disease) nor is it the only mechanism responsible for many of the covid symptoms," says Cequier, who believes that saying that the conclusion is that it is a vascular disease is "a bit of a superficial interpretation". 

Why is it not exclusively vascular?

Vascular diseases are those in which the arteries or veins are affected and, in most cases, also the blood flows, either by blockage or weakening of the vessels or by damage to the valves in the veins. Although covid-19 sometimes affects the heart and circulatory system with thrombi, it is not a vascular disease. If it were, says Cequier, "it would cause acute myocardial infarctions, or many arterial embolism, both of which are rare in covid," he argues. 

What is more common is that through the whole inflammatory cascade that takes place after an infection and is a consequence of the immune system, "very diffuse" damage is produced and ends up affecting the heart, which can lead to "an alteration of the coagulation system" and, therefore, to "an increased risk of thrombi formation, which is associated in turn with thromboembolism", concludes the cardiologist.