Professor Fiona Lyons:

In order to get 0.5 ml to try to get five doses out of a vial, a particular needle and syringe has to be used, which we had to source and have been sourced. There is not a guarantee of actually getting five out. It is a fiddley thing is the best way to describe it. The experience has been that people are mostly getting about four doses out per via,l but there are some circumstances where there were it may be three. In some circumstances, it may be up to five. It is literally that we are using a vial that was only ever meant to be for extracting one dose, dividing its contents into five and trying to get as many as possible out of it. That is why there is the range of around three to five.