ACE2 receptors, through which the virus infects the cells, are highly expressed in parts of the lung and the digestive tract. They are not in the upper respirat

ACE2 receptors, through which the virus infects the cells, are highly expressed in parts of the lung and the digestive tract. They are not in the upper respiratory tract however. The accuracy of the swab test depends on the amount of viral material coughed up in the sputum.