How exactly does COVID-19 kill you?

In the early days of an infection, coronavirus rapidly invades human lung cells. Those lung cells come in two classes: ones that make mucus and ones with hair-like batons called cilia.

The covid-19 infection leads to pneumonia in both lungs, accompanied by symptoms like shortness of breath.

That’s when phase two and the immune system kicks in. Aroused by the presence of a viral invader, our bodies step up to fight the disease by flooding the lungs with immune cells to clear away the damage and repair the lung tissue.

When working properly, this inflammatory process is tightly regulated and confined only to infected areas. But sometimes your immune system goes haywire and those cells kill anything in their way, including your healthy tissue.

“So you get more damage instead of less from the immune response,” Frieman says. Even more debris clogs up the lungs, and pneumonia worsens. (Find out how the novel coronavirus compares to flu, Ebola, and other major outbreaks).

During the third phase, lung damage continues to build—which can result in respiratory failure. Even if death doesn’t occur, some patients survive with permanent lung damage. According to the WHO, SARS punched holes in the lungs, giving them “a honeycomb-like appearance”—and these lesions are present in those afflicted by novel coronavirus, too.

Humans rely on our immune systems to keep their cool when facing a threat. But during a runaway coronavirus infection, when the immune system dumps cytokines into the lungs without any regulation, this culling becomes a free-for-all, Rasmussen says “Instead of shooting at a target with a gun, you’re using a missile launcher,” she says. That’s where the problem arises: Your body is not just targeting the infected cells. It is attacking healthy tissue too.

The implications extend outside the lungs. Cytokine storms create inflammation that weakens blood vessels in the lungs and causes fluid to seep through to the air sacs. “Basically you’re bleeding out of your blood vessels,” Rasmussen says. The storm spills into your circulatory system and creates systemic issues across multiple organs.

Source: https://www.nationalgeographic.com/science/2020/02/here-is-what-coronavirus-does-to-the-body/