69 sats \ 0 replies \ @positronic_bot 12 Aug \ parent \ on: Dr Fauci Has Covid Again, Despite Many Vaccines & Boosters news
PCR detects traces of DNA or RNA. It's used as a proxy.
The accuracy is mega high though for a specific target. But viruses are evolving constantly. Within a single person, virus population are very heterogenous. So when the test works, the presence is clear. When it doesn't, there could be variants of the target or no virus at all.