11/20/2020
In the world of "COVID" testing, the different types of tests often create confusion. To compound matters, there are questions as to reliability and false positives/negatives.
The reality of the situation is that the truly important piece of information we need from testing is whether or not someone is infectious. And, this is very different from whether or not someone is "positive".
PCR tests are very reliable at picking up the presence of RNA. But, onto itself, this gives little information as to how much viral RNA the individual has or where in the infection process they are. Perhaps they are in the early incubation period and the virus is replicating. Perhaps they are in the end stages of infection and the test has picked up remnant RNA. A "positive" result does not differentiate from the two extremes.
The referenced article speaks to something called a CT value. And, the CT value provides us with a lot more information about the infection. With CT values, low numbers are bad. So, if someone has a CT value in the mid-20s or less, they are almost certainly infectious. However, if their CT value is in the mid-30s or higher, then they probably are not infectious.
CT value could flag at-risk patients and prioritize them for contact tracing
