The body detects the thick, toxic mucous and generates a cough to drive the mucous out of the throat and trachea before it gets into the lungs.
It has two purposes:
In the early stage, when the infection is only in the upper respiratory system, sinuses, nose, and throat, the body generates mucous on those tissues. If we sneeze, spit it out, or cough, we are getting virus out of our system, which is good for our personal health. (Let’s do it cleanly, so we don’t infect anyone else!) If we swallow the mucous into our stomach, that may be uncomfortable, but the stomach will kill the virus. But if the mucous runs down the trachea, then that puts the lungs in danger of infection. This is very dangerous.
If the disease gets worse, we get a lung infection (technically, any lung infection is called pneumonia).
Now the body coughs even harder. It is trying to force mucous up and out of the lungs. This both clears the lungs of fluid so more air can get in and also kicks out virus particles, reducing infection. If the cough and the body succeed, then the virus is driven out or killed off. If the body doesn’t succeed, then we get sicker.
There are two dangerous steps:
- If the lungs start to fill with fluid, we need oxygen, which generally means hospitalization. If that is not enough, we can go into a danger of acute respiratory failure, where if we do not get put on a ventilator, we die. And if we do get put on a ventilator, our odds of living are only about 50/50 at that point.
Both of these crises can happen very suddenly and disorient the patient. So, anyone with COVID-19 who is coughing and feeling week needs constant monitoring. If he or she becomes incoherent or can’t be woken up, call emergency services immediately.
If the person recovers, then the dry cough may last some weeks as the body works to clear the toxic mucous from the lungs and upper respiratory system.