To follow up on this international theme, obviously everybody wants to be done with COVID and wants to understand what they can start to do if they're fully vaccinated. We are starting to see bits and pieces of this in different countries around the world. I know it's something you're looking at too, in the immunity data. However, the challenge I have is that sometimes this can be a bit unhelpful in the sense that if we don't have a recognized sense of immunity understanding, some jurisdictions can say you can do x or y, and can then pull that back.
Do you see that as a challenge, this constant struggle? Everybody obviously wants to travel or do things again. Where do you see us, in understanding the immunity data, with vaccines, taking into account the variants? Maybe that's an unfair question, but it's about a balance between moving ahead and having some kind of unified understanding of what immunity means when you're fully vaccinated.