The p24 antigen peaks around week 3 from what I've read. ( It starts falling off after that and supposedly by week 6 it's gone). A few days later, you get a IgM antibodies and at the end of the 4th week, you usually have p24, IgM, and IgG present.
But this is a statistic. Some people take a few days longer and some people take a few days less.
When you do a DUO test, at 28 days you can reasonably expectant that enough time has passed to statistically that all 3 will be present. Moreover, the test is looking for all 3 things.
This means to get a false reading, it would mean that all three things are there i.e. an infection, but the test failed to detect all 3.
So by waiting the extra time, you're giving everything a chance to work and thus reduce the chance of missing something.
If you rely strictly on a p24 at 2 weeks, then you're facing two things. Variance in how a particular infection is going to behave in a particular human body and the possibility of a sample error for a test because it failed to detect p24.
Be well
The test is too new and overall we are not involved in testing here.
ok so the result can change , has it ever been seen here on this forum ? and 16 days is just half the time of a conclusive test , i dont understand why is it said that the antigens strt falling off at week 4 but still NOT detectable at 2 weeks proceeding to 3 ? Lets be logical here... a person who have been actually infected would have had detectable antigens at least at a 16 day mark ????
14-16 days is a good indication, but it's not conclusive. A negative at 14 days could indeed become a + at 28 days. ANY neg along the way is a very good sign.
If you're testing with a DUO., 28 days is conclusive. That simple. Try not to read more into it than you need.