Both tests have value, but the virus RNA test is fast and accurate. We just need millions more!!
∆ The RNA in the virus is its unique operational instructions. The RNA test detects some of this material.
∆ This PCR test can detect one unique RNA segment among billions of others, and cyclically amplify it so that it can be measured.
∆ The test is very specific and very sensitive, meaning very few false positives or false negatives.
∆ In contrast, viral culture requires a lab that is qualified and approved for that purpose. Live cultures are potentially infective.
∆ The culture test can determine if "living" virus are present. However, the false negative rate is a hazard of test interpretation.