SARS-COV-2 binds to ACE2 receptors which are prevalent in your lungs and your gut. Its possible the virus attacked the gut rather than the lung. Staring at data last night there's about 1/4-1/3 of a chance for "mild symptoms" but the data did not capture gastrointestinal issues. This also goes along with the theory that there are two strains, one more vicious than the other.