We usually point to it. There's also one that was established by the CDC, so we tend to observe both definitions. It just becomes a question of whether you use the cut-off of four weeks or 12 weeks, and this is really something of debate, because you do see a lot of improvement between four and 12 weeks for a subset of patients. Almost 40% to 50% have this improvement, but then you're left with this other significant chunk of patients where COVID persists for a long time.
As you go beyond that 12 week cut-off, you start to see that the curve plateaus, and then you see what really looks like the phenomena that is a chronic illness.