1. PCR (NAT) tests directly look for the virus in the body unlike the Antibody test which looks for the body's response to the infection
2. PCR tests can tell you if your body is infected as early as 72 hrs after the exposure
3. PCRs are lately approved for diagnostic purpose however doctors may order for NATs if they feel that one is going through ARS since it enables appropriate treatment by early detection of the virus
4. Theoritycally PCR can detect the virus as early as 72 hrs after the infection and the detection just keeps getting better along with the time since the HIV virus replicates itself in millions every day which means viral load keeps increasing every single day after the infection. For practical purposes one should wait atleast for 10 - 12 days aftr the exposure in order to get a PCR test
5. Comparisn RNA PCR / DNA PCR:
Another type of test is an RNA test, which detects the HIV virus directly. The time between HIV infection and RNA detection is 9-11 days. These tests, which are more costly and used less often than antibody tests
But RNA (viral loads) can become not detectable in some (meaning not many) cases when the body finally fights back. But on the other hand PCR DNA tests are best used from 28 days on, but as early as 2 weeks, b/c these levels will not become none detectable over time.
So in short less then a month or during ARS, PCR RNA tests is best (9 -11 days after the exposure) but after a month a PCR DNA test would be best, but at this point an Elisa test would work just as good and without the risk of false positive which would make most people here go crazy.
6. RNA PCR is for early detection, test at the 14 th day after the exposure backed up by an antibody test at the 6-8th week is good enough to rule out HIV.
DNA PCR at the 28th day after the exposure backed up by an antibody test at the 6-8 th week is good enough to rule out HIV
Both are NAT tests and are highly sensitive.
7.Drawback(very very unlikely though)
In some HIV positive individuals there are cases of undetectable viral load however a hypersensitive viral load test ( sensitivity - 50 copies / ml, 10 copies / ml) are good enough to detect the presence of the virus in the body.
8.Misconception about the PCR test (False Positives)
False positive rates have drastically dropped and every positive PCR is confirmed with another PCR for confirmatory reason, this eliminates the possibility of false positives, they are very reliable after 28 days, your result would be conclusive, however just for your own peace if mind back it up with a confirmatory test at the 8th week and move on.
In a nutshell, if you have the money to spend RNA PCR is a great test but one has to back it up with an antibody yest for confirmatoty reasons only.
As per my research, Most of the experts haven't seen a negative PCR result changing ahead.
PCR RNA test is to help with early diagnosing. It is not a stand alone test and must be followed up with an antibody test.
In adults, adolescents, and children infected by other than perinatal exposure, plasma viral RNA nucleic acid tests should NOT be used in lieu of licensed HIV screening tests (e.g., repeatedly reactive enzyme immunoassay). In addition, a negative (i.e., undetectable) plasma HIV-1 RNA test result does not rule out the diagnosis of HIV infection.
I think you should call up your local HIV/ AIDS help line for that info and I don't think there's any more info that we can add to RNA PCRs.
I'll sum that up for your reference one more time;
RNA PCR is a great indicator and a negative (undetectable) result is highly unlikely to change however it has to confirmed with an antibody test for confirmatory reasons.
An undetectable RT RNA PCR changing ahead needs a lottery - win luck !
It's not 99.9 % accurate however a great indicator of what your antibody test result at the 12 weeks is going to be.
Most of the experts now a days rely on PCR while treating HIV cases for early detection
A negative (undetectable) PCR result changing ahead is some thing which's unheard to most of the experts
Most of the websites and experts talking about PCR tests do not keep it in to consideration that, today almost every where they rely on the real time hypersensitive PCRs having a sensitivity of 10 copies /ml , 50 copies / ml....etc which is highly sensitive and not the earlier PCRs with 500 copies / ml , 1000 copies / ml....
So, PCRs are a great test, if you have the money to spend and they are getting better every day.
Jimmy, I'd say ease up, your antibody rest will be negative too, I guarantee.
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