Yep CDC says not to use test as a sole determinant of anything. It is only one part of the evidence and may be flawed for a variety of reasons From the World Health Organization (WHO): “Coronavirus disease (COVID-19) technical guidance: Laboratory testing for 2019-nCoV in humans” https://bit.ly/3cidWiS “Several assays that detect the 2019-nCoV have been and are currently under development, both in-house and commercially. Some assays may detect only the novel virus [COVID] and some may also detect other strains (e.g. SARS-CoV) that are genetically similar.”
Again:
some may also detect other strains (e.g. SARS-CoV) that are genetically similar