As yet, there is no such biomarker and despite some promising research, there is still no test that can reliably separate people with ME/CFS from people with other, similar diseases. We know that others around the world (e.g. Stanford, Harvard and Uppsala) are actively pursuing biomarker research, and we hope they are successful. But there is no guarantee of success and the timescale to development is uncertain. So, it is our view that we should press ahead with our complementary approach.