Why are people infected with COVID-19 reporting that they began to feel better before becoming critically ill?

《美国CDC网》 April 16, 2020

Most likely this is because, like any other flu, Covid-19 enters the upper respiratory system and gives you what seems like the sniffles and a shrunken head associated with sinus pressure. This condition clears in a few days and you feel better as the virus makes its way down into your trachea, lungs and stomach.

In some cases it messes with the flora of the gut and you get diarrhea. Over the next few days it begins to replicate in the lower respiratory system. If your immune system is healthy, it will go into fight mode and battle the infection in the ’upper-lower’ respiratory. You may get a fever, feel weak and develop a dry cough, as your lungs try to expel the dead cells. If all proceeds normally you will cough up a bunch of mucus (probably a little greenish) and transition into a ‘healthy’ chest cold. In some cases it never even gets to that. If it does, at this point you are in high transmission mode. Stay home. Don’t kiss anyone.

This is the same pattern as Influenza and other corona-viruses (SARS, Swine Flu, etc.). That’s why the parental advice CDC is giving you is the same that your mom gave you when you were 5 (wash hands, cover mouth, don’t lick strangers)..

What seems to happen next is that the virus is above average at replicating itself. And it remains in the body for quite some time. So you feel a bit wrecked and this can go on for a week or more. If the body wins (most patients do), then you get better and develop antibodies that keep the virus at bay until it dies. This can take a week or longer and it can be very unpleasant. If u aren’t winning after a week, there is likely a serious issue.. See a doctor.

In acute cases, virus replication is faster than the speed at which the antibodies kill the copies. In extreme cases, your body can no longer distinguish infected lung cells from healthy ones and starts to kill everything. That is the final stage of Viral Pneumonia, which is what all critical virus infections result in.. Influenza, SARS, etc..

Pneumonia is quite common. Last flu season we had over 1M cases and over 400,000 hospitalizations and about 50,000 deaths. So listen to your body, stay warm and all the best to you.