ABOVE: Scanning electron microscope image of SARS-CoV-2 (gold) emerging from the surface of cells cultured in the lab. The virus shown was isolated from a patient in the US. Image captured and colorized at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, Montana
FLICKR, NIAID
One of the most striking features of SARS-CoV-2, the virus that causes COVID-19, is the exceptional breadth of symptoms it causes in people. Of the nearly 30 million recorded infections to date, the vast majority of people experienced mild or moderate disease—which itself can range from no symptoms at all to pneumonia or long-term, debilitating neurological symptoms. A minority ended up with severe respiratory symptoms but eventually recovered. And some—nearly 940,000 worldwide, of which 196,000 are in the US—took a turn for the worse and died.
Why some people die while others recover is thought to depend in large part on the human immune response, which spirals ...
