 When I think about the different phases or generations of vaccines, you've got for COVID, for example, you've got the current vaccines that are licensed now, the front runners, and I will call them the first generation. You've then got the next wave or generation of vaccines, which is trying to adapt the current vaccines to the new variants to make them expand their targets to cover the next variants. And then you've got kind of thinking down the line a little bit to maybe third generation vaccines about how do we manage COVID longer term, thinking three to five years? How do we develop vaccines which cover multiple variants or which cover and can protect against multiple coronaviruses? It's important to evolve and adapt the vaccines to what the need is.