Study Explains Immune Response in Asymptomatic Cases of COVID-19

 

It has always puzzled me how one can be infected with SARS-CoV-2 and not show any symptoms. After all, the bug has invaded you and has hijacked your cells to make copies of itself, rather than doing what they're supposed to be doing. How can that be?

A new study just published in Nature Medicine sheds some light on the matter.  The authors claim it is the first study to compare the immune responses of people who have no symptoms to the immune responses of people with a more serious infection.

The actual study is full of big words that are probably only meaningful to an immunologist. Fortunately a helpful science reporter has dumbed it down to the point where I can understand it.  

Essentially, people who have asymptomatic infections have high levels of B cells (a type of white blood cell) in their noses and other mucous passages. These cells detect pathogens and help initiate an immune response. These cells were missing in people with more serious infections.

People who were hospitalized had more immune cells of the type that can lead to inflammation and tissue damage. They also had increased levels of platelet-producing cells, which help blood to clot.  Clots are a known problem with COVID-19, and are responsible for lung damage and strokes (among other maladies) in victims .

So, it looks like people who are asymptomatic are doing a better job of fighting off the disease and keeping it in check when they are first infected. This helps explain the fact that asymptomatic people are less likely to spread the disease. They remain without symptoms because the infection never escalates to the point where it causes inflammation that we feel as symptoms. 

Image by Bruno /Germany from Pixabay 

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