We want to find out, scientists to scientists, exactly what is going on, but it's something that has emerged in South Africa and seems to be spreading at a reasonably rapid rate, in the sense of when they do test positivity they're seeing it's a bit more widespread in South Africa than was originally felt a couple of days ago. So it's in a fluid motion. We're finding more about it and, literally, it's something that – in real time – we're learning more and more about.