Secondary bacterial infection of the lung (pneumonia) was extremely common in patients with COVID-19, affecting almost half the patients who required support from mechanical ventilation. By applying machine learning to medical record data, scientists found that secondary bacterial pneumonia that does not resolve was a key driver of death in patients with COVID-19. It may even exceed death rates from the viral infection itself. The scientists also found evidence that COVID-19 does not cause a "cytokine storm," so often believed to cause death. "Our study highlights the importance of preventing, looking for and aggressively treating secondary bacterial pneumonia in critically...