One of the issues may be that you could test positive for Covid at different times with the different tests:
For example with the PCR test you might test positive after 48 or 72 hours. With the cough test it might take longer for it to start to effect your lungs - another 24 or 48 hours. It doesn't meant the test is not useful.
COVID-19 Instant Screening test, page-4
Currently unlisted. Proposed listing date: 4 SEPTEMBER 2024 #