The corona virus leads to life-threatening symptoms in some patients. What exactly happens with an infection in the body and why do the course of the disease vary so much?
From asymptomatic to fatal lung failure: the course of a corona infection varies widely. Not only previous illnesses, but also the type of infection could play a role in the severity of the course of the disease.
First of all, we have to understand what happens in our body after being infected with the lung disease Covid-19.
Coronavirus: what happens in the body?
As virus researcher Professor Matthew B. Frieman from the University of Maryland School of Medicine explains, the coronavirus attacks the lungs in three different phases.
Phase 1: Virus multiplies in the lungs
After infection, the virus first spreads to the lungs of the infected person and affects the mucus-producing goblet cells and the cells with cilia. The latter have the task of transporting foreign substances from the lungs.
However, the cilia are killed by the virus. As a result, more and more foreign substances and viruses collect in the lungs in addition to the dead hairs.
Phase 2: Immune system becomes active
The body now reacts to the foreign substances and viruses with masses of immune cells that are supposed to kill the viruses. The infection is combated by the immune reaction and, in the best case, completely contained.
However, it becomes problematic when there is an overreaction of your own immune system. This overreaction also kills healthy tissue. The defense reaction gets out of hand.
Phase 3: Lung tissue is destroyed
In the last phase of the infection, the lungs are massively damaged. Because the virus eats holes in the lung tissue. Due to the destruction of the lung tissue, fluid can enter the lungs. This leads to respiratory failure, from which the sick person can die in the worst case.
In some cases, the uncontrolled immune response triggered by the corona infection can damage other organs not only in the lungs. Many corona sufferers also complain of diarrhoea.
That is why the course is so different
Many patients do not go through all three phases of the infection. Therefore, the severity of the course of the disease can vary widely, from asymptomatic to fatal.
Virologist Christian Drosten estimates that the type of infection could also be decisive for the course of the disease:
If the coronavirus is absorbed through the oral mucous membranes, for example, the virus then migrates from the throat to the lungs.
By this time, when the virus is moving from the throat to the lungs, your body can already make antibodies against the virus. As a result, the virus can no longer do as much damage to your lungs.
Infection via the oral mucous membranes could therefore protect against bad courses that are associated with infections of the lungs.
However, if you breathe in the virus, it can nest directly in your lungs. The risk of a serious course of the disease is greater in this case because your body has less time to produce antibodies.