Hot off the presses, a little good news about anosmia, loss of smell. https://archive.is/dqhGD

tldr: While colds, flu, sinusitis can all cause loss of smell due to one mechanism, obstruction and swelling, Covid 19 has another mechanism. It attacks the substrate supporting the olfactory nerves. This can even lead to loss of the peripheral olfactory nerves. The somewhat good news is that they regenerate. The not so good news is that it takes a long, long time. And though it doesn't say so here, possibly in some cases the substrate destruction can't be overcome.