COVID-19 is more a blood clotting disorder than just a bad form of lung infection. SARS-CoV-2 was initially presumed to be primarily a bad form of acute lung injury. It is now classed more as a thrombotic [clotting] disorder – which is unusual in viral infections. What determines its severity is the degree of blood clotting – which potentially leads to stroke and heart attacks. The clots also threaten an increased risk of neurological complications like memory problems and confusion.