The key thing here is that you can take a blood sample, for example, and then very easily analyze the likelihood of that person will be protected based on this one easy to measure by a marker. And that really makes so many things easier to do in terms of developing new vaccines or even fighting variants. People have told me that maybe we don't need to completely understand the mechanisms of protection from most vaccines. That's a statement that peoplehave kept telling me over and over again. But even a bit of understanding of how a vaccine works,. why it's protecting, will help you make sense of this number you decide as your correlate of protect but i think the bottom line, as you say