What Is A Cytokine Storm?

Cytokines are small proteins. They allow cells to communicate with each other. When a virus enters a cell, that cell releases cytokines. And some of these cytokines are responsible for causing inflammation, while others travel through your blood system to recruit white blood cells to the area of invasion. And this creates even more aggressive inflammation of the invaded tissue.

Initially, this response is good. It is how cells and tissues kill invaders. It is how cells and tissues heal themselves. Although, when cytokine levels remain elevated, they start to do more harm than good. Cytokines, when left unchecked, become cytotoxic. This means that they start to damage the same tissues they are meant to protect.

So, COVID-19 tends to cause the over-production of cytokines procured by white blood cells. This is called a cytokine surge or cytokine storm. It is this storm that is responsible for the development of Acute Respiratory Distress Syndrome (ARDS). And this storm may continue even after patients even as these patients move into post-COVID status.

It also causes what is called endothelitis. This is a condition where the inside walls of blood vessels become inflamed. This causes vasoconstriction. This sets up an environment where your blood more easily clots (hypercoagulability). It also causes less blood to get to organs (hypoperfusion). And this means less blood gets to organs (Ischemia). And this is what leads to shock and death.

A cytokine storm can be caused by other diseases. Although, this seems to be more prevalent with COVID-19. 

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References. 

1. Jain, Uday, "Effect of COVID-19 On The Organs," Curius, August 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7470660/, accessed 12/ 22/2021