 This pandemic has seen us develop a new type of vaccine, the mRNA vaccines. I wonder if you could talk through your way of explaining how those work, because they are a new type. What it is, is the recipe to make the spike protein. So you literally inject the recipe for the spike into your muscle, and your body reads off that recipe and makes lots of spike protein. This is a viral protein. Now remember, there's no virus there, it's just the spike. I can't make you sick, it's not like getting infected. But now you make the spike, and now your immune system makes antibodies and T cells to recognise that spike protein. So it's remarkably simple in a way. And certainly the Pfizer one is the first time an RNA vaccine has been approved for use, and now it's been used in millions of people. So it's a great example of sort of basic discovery, I suppose, giving rise to a whole new approach. I'd also say, Anna, that they decided to try it, because other approaches had failed previously with things like the common cold. Now this virus, as we all know by now, is in the same family as the common cold virus. So hence there was a need for brand new technology, and that's what this RNA approach was with.