How does the coronavirus kill? Scientists still don't know

scientists do not yet know exactly how the coronavirus kills

More autopsies were needed. With 4.3 million infected and more than 297,000 dead worldwide, scientists do not yet know exactly how the coronavirus kills. What they are clear about, however, is that if you want to understand how the disease is affecting the different organs, the most effective way is to do as many autopsies as possible.

And there, precisely, is where the problem is. As the magazine « Nature » points out, the urgency of the situation, with thousands of patients saturating the capacity of hospitals, has greatly slowed down the rate at which autopsies are carried out . Literally, there is almost no time to do them, nor enough hands to dedicate to the task. Furthermore, being an infectious disease, contact with corpses that can still transmit the virus requires additional security measures, which further complicates the ability to do all the autopsies that would be necessary.

Puzzling effects on the heart and kidneys

Since the start of the pandemic, researchers around the world have flocked to study Covid-19, a disease that primarily attacks the lungs but also has puzzling effects on the heart, kidneys, and brain. And the blockages and confinements with which the world tries to stem the pandemic have further complicated efforts to collect the tissue samples that researchers need to understand how the coronavirus can wreak such havoc.

But pathologists desperately need those tissues to determine what exactly is killing patients. Is it pneumonia? Blood clots? A massive immune response? Also, why do many develop kidney failure? And what about children? The truth is that, regardless of who regrets it, these are questions for which there are still no clear answers.

The compilation article that a team of researchers from the Zunyi Medical University in China has just published in the journal " Frontiers in Public Health " is very interesting in this regard . It reviews the epidemiology, symptoms, diagnoses, and current treatments used to treat the most severe cases of Covid-19. In other words, everything that is known today about how the coronavirus works and how it kills.

The important role of the immune system

In their study, the researchers highlight the important role that the overreaction (and potentially lethal) reaction of the immune system of infected patients has. Many, in effect, die victims of what their own bodies do to try to defend themselves from the virus. Experts explain step by step what is known about how the virus infects the airways, multiplies within cells and, in more serious cases, causes the body's defenses to trigger a veritable " cytokine storm ", the product of a over-activation of white blood cells which, in these circumstances, release too high amounts of these molecules into the blood whose role is to stimulate inflammation.

MODS

Cytokine storm causes high fever, loss in blood vessels, clotting of blood within the body, very low blood pressure, lack of oxygen, excess acidity of the blood, and accumulation of fluid in the lungs. In this dramatic situation, white blood cells "go crazy" and even attack healthy tissue, leading to failure of the lungs, heart, liver, intestines, kidneys, and genitalia. Doctors know this condition as Multiple Organic Dysfunction Syndrome , or MODS.

And it can get even worse. Sometimes, the remains of proteins and cells killed by white blood cells can cover the lungs with a thin layer (the hyaline membrane) that hinders the absorption of oxygen. The lungs shut down and acute respiratory failure occurs, ending the patient's life. Most Covid-19 deaths follow this terrible pattern.

Filter blood to save life

In their article, the researchers state that, in the absence of a specific antiviral cure, the goal of treatment should be to combat symptoms, and reduce the death rate by maintaining organ function at any cost . For example, an artificial liver blood purification system or renal replacement therapy, filtering the blood by mechanical means. Not to mention methods of supplementing or replacing lung function, either through mechanical ventilation (with masks or tubes into the trachea) or by administering warm, moist oxygen through a tube inserted into the nose.

Treatments are generally very aggressive and do not always achieve recovery for patients.

In summary, the study explains that severe coronavirus patients can die in very different ways and from failure of the lungs, heart, liver or kidneys. This is why it is so important to find out exactly how the deadly machinery of the virus works. In «Nature», the experts advocate, as already mentioned, for an exponential increase in the number of autopsies. For this reason, and at the same time that researchers are struggling to understand the many effects of Covid-19 on the human body, they are increasingly demanding more access to more samples from patients.

In many hospitals, the demand for tissues has increased since the early days of the pandemic, but it has been materially impossible to do the necessary number of autopsies. And the available samples are distributed by dropper, so that many doctors have no opportunity to examine them.

To determine exactly what is happening in the infected organs, researchers need large numbers of samples. Even before this era of coronavirus, autopsies answer questions that may be vital to a patient. And now, with a new and unknown disease, autopsy information could be critical to all of humanity.