Just because they tested positive at week 15, it doesn’t necessarily mean that that is a true positive. Also, they may have taken antiviral therapy that impacted their seroconversion time. It’s really impossible to tell the exact truth from posts to I have given up trying.
If you want to know the exact index value of your negative, you should ask the lab directly for those numbers. If they won’t give it to you, you’ll have to go through the ordering provider. The test code is the same, it’s just that not all labs report out the exact value.
Terri