Severe cases of Covid-19 have been known to lead to a mysterious condition whereby the body's immune system goes haywire and starts attacking healthy cells, rather than just those that are infected. This prolonged state of self-sabotage is known as a 'cytokine storm' and can be fatal, but researchers have struggled to understand how it works and how to treat it. Now new research has looked at the progression of a coronavirus infection in mice and found the cytokine storm is a vicious cycle, which leads to the overproduction of two signalling proteins called tumour necrosis factor (TNF)-alpha and interferon...