Why do we lose our sense of smell?

The week's science news with Dr Chris Smith and the Naked Scientist team. This week:

How close are we to being able to grow complete new arms and legs? New research looks very promising in this direction. And a breakthrough in sight restoration: we take a look at the patient who’s received a bionic eye

Plus, in the wake of Covid-19, millions of people have suffered smell and taste loss; for some it’s never returned, and others are left living in a world that doesn’t smell, or taste quite right; how can we help them?