And so we're really looking what are sentinel surveillance sites. I think we can see where there's outbreaks, because once people have symptoms, you can see them. But where do you do sentinel surveillance so that you find them before they have symptoms. This is what we have done for decades in HIV, and it's what's allowing us right now to really control the HIV/AIDS epidemic in Sub-Saharan Africa, because we're finding people when they're asymptomatic and treating them when they're asymptomatic. So this is something we know how to do and it's something we're working very closely with CDC and others on to make sure that we can bring that full capacity to the American people.