Since no quantified virus isolates of the 2019-nCoV were available for CDC use at the time the test was developed and this study conducted, assays designed for detection of the 2019-nCoV RNA were tested with characterized stocks of in vitro transcribed full length RNA
Just ask the CDC
Page 42, second paragraph. https://www.fda.gov/media/134922/download
https://peopleforjusticecanada.com/2021/01/05/canadian-public-health-officials-have-no-record-of-sars-cov-2-isolation-purification-performed-anywhere-ever/