So finally: why did we do the PCR design this way? Because it was January 6th, we were hearing of a new SARS like virus, and there were no samples, viruses outside of China, yet we needed to make sure to be ready for testing (and were asked to do so in travellers).

The labs on this paper all had worked with SARS, had samples from SARS patients in their freezers. So that made it possible to do a first check of how this would work. A valid choice in an emerging disease outbreak, where you are in the blind phase.

And also because SARS was eliminated. So, yes, these tests are positive in people with SARS COV 2. And now back to real work.