On Jan. 15, 2021, scientists at Washington University School of Medicine in St. Louis announced that that a relatively simple and rapid blood test can predict – within a day of a hospital admission – which patients with COVID-19 are at highest risk of severe complications or death. The study, published Jan. 14 in JCI Insight, involved nearly 100 patients newly admitted to the hospital with COVID-19.

The blood test measures levels of mitochondrial DNA, a unique type of DNA molecule that normally resides inside the energy factories of cells. Mitochondrial DNA spilling out of cells and into the bloodstream is a sign that a particular type of violent cell death is taking place in the body.