Why does Covid make us lose our sense of smell?

"My anosmia came on very suddenly. For three months, I felt absolutely nothing. Eight months later, I haven't recovered 50% of my sense, so I still have a long way to go," says Nina, 28. Anosmia, or total loss of smell, is one of the symptoms of Covid-19. While most people quickly recover this sense after the disease, a minority may be affected by olfactory disorders over a longer period.