Long Covid could be caused not by an active virus, but in long lasting changes to the body caused by a prior infection. One could imagine (entirely hypothetica

Long Covid could be caused not by an active virus, but in long lasting changes to the body caused by a prior infection. One could imagine (entirely hypothetically) that a subset of COVID infections destroys all of the cells in the nose used generate further cells that detect smells. This would result in a permanent loss of smell, but fixing it require something different than just removing the virus from the body.