Advertisement In people dying from Covid, they added that studies have also observed sections of their lungs die after their vital blood supply is cut off due to clots. On the other hand, the key features of pneumonia - thickened lung walls and mucous in the small airways - are not present in Covid cases. 'In summary, the radiological findings are not consistent with dominant or primary airways disease but rather are entirely consistent with a disease of the lung blood vessels occurring first,' they write in the paper. Professor Chapple said gum disease and cavities make it easier for bacteria and viruses to enter the body.