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Is HIV P24 Antigen Test Done 13 Days Post Exposure Conclusive?
Question: I'm sorry to bother you again and based on our discussions that I'm fine.
But for peace of mind I took a XXXXXXX test a test 9 1/2 days that the Dr said was non reactive and highly sensitive. Then I did Rapid P-24 antigen that he said is very accurate at 14-21 days. It was non reactive at 13 1/2 days.
This dr of stds says I should be rock solid bullet proof. Do you agree? And since both these tests were negative would it make the odds even better and mean I should need to do nothing again in several weeks? Thanks
But for peace of mind I took a XXXXXXX test a test 9 1/2 days that the Dr said was non reactive and highly sensitive. Then I did Rapid P-24 antigen that he said is very accurate at 14-21 days. It was non reactive at 13 1/2 days.
This dr of stds says I should be rock solid bullet proof. Do you agree? And since both these tests were negative would it make the odds even better and mean I should need to do nothing again in several weeks? Thanks
Brief Answer:
Regarding HIV screening
Detailed Answer:
Hello. Thank you for writing to me.
I am happy to answer all your queries
First of all, the nature of your contact dies not even warrant HIV screening.
Nevertheless, the PCR RNA for HIV and P24 Antigen test are very sensitive tests and a negative result is fair to conclude HIV status depending on the level of risk exposure, however with these tests I usually suggest a waiting period of 2 weeks after contact (window period of RNA PCR is 9-13 days i. e roughly 2 weeks and same is the case with P24 Antigen. P24 antigen is at its peak at about 2-3 weeks and later starts to decline to undetectable levels at 8 weeks as anti HIV antibodies start to form at 2 weeks. So 2-3 weeks is the ideal time to do a P 24 antigen screening test).
As I already said, neither RNA PCR nor P24 antigen screening are ideal to rule out HIV as they may be negative early on in infection. HIV DUO (4th generation screening test) which is a combination of P24 antigen and anti HIV antibody screening is a more sensitive and specific screening test than NAAT screening or P24 antigen. Moreover it simultaneously tests for 2 different markers of infection and picks up 95% of new infection at 3-4 weeks. In most cases this is enough depending on the exposure risk. However in high risk exposures e g unpritectex vaginal or anal sex with a commercial sex worker it is recommended to also go for a 3rd generation HIV antibody test at 12 weeks. The antibody test at 12 weeks picks up 99.9% of new infection. This is the most conclusive out of all.
Regards
Regarding HIV screening
Detailed Answer:
Hello. Thank you for writing to me.
I am happy to answer all your queries
First of all, the nature of your contact dies not even warrant HIV screening.
Nevertheless, the PCR RNA for HIV and P24 Antigen test are very sensitive tests and a negative result is fair to conclude HIV status depending on the level of risk exposure, however with these tests I usually suggest a waiting period of 2 weeks after contact (window period of RNA PCR is 9-13 days i. e roughly 2 weeks and same is the case with P24 Antigen. P24 antigen is at its peak at about 2-3 weeks and later starts to decline to undetectable levels at 8 weeks as anti HIV antibodies start to form at 2 weeks. So 2-3 weeks is the ideal time to do a P 24 antigen screening test).
As I already said, neither RNA PCR nor P24 antigen screening are ideal to rule out HIV as they may be negative early on in infection. HIV DUO (4th generation screening test) which is a combination of P24 antigen and anti HIV antibody screening is a more sensitive and specific screening test than NAAT screening or P24 antigen. Moreover it simultaneously tests for 2 different markers of infection and picks up 95% of new infection at 3-4 weeks. In most cases this is enough depending on the exposure risk. However in high risk exposures e g unpritectex vaginal or anal sex with a commercial sex worker it is recommended to also go for a 3rd generation HIV antibody test at 12 weeks. The antibody test at 12 weeks picks up 99.9% of new infection. This is the most conclusive out of all.
Regards
Above answer was peer-reviewed by :
Dr. Raju A.T
I think I understand you believe I am at no risks, with what you would suggest were non penetrative acts
But do you believe after the 2 early warning tests that highly likely at least 1 of the 2 would have caught a problem?
The dr of vernilogy like you says he has never had one person negative on these tests come back positive on a later tests. The technician told me almost always if positive it shows on the testing materials immediately. I guess after 2 tests not 1 I'm wondering if the likelihood of inaccuracy is nearly nil. Sorry for my persistence
And what does sensetvity and speceticity mean in laymens terms?
And how do the first two tests I took get interpreted in this regard?
Thanks as you can tell the worry is terrible even with your reassurances
But do you believe after the 2 early warning tests that highly likely at least 1 of the 2 would have caught a problem?
The dr of vernilogy like you says he has never had one person negative on these tests come back positive on a later tests. The technician told me almost always if positive it shows on the testing materials immediately. I guess after 2 tests not 1 I'm wondering if the likelihood of inaccuracy is nearly nil. Sorry for my persistence
And what does sensetvity and speceticity mean in laymens terms?
And how do the first two tests I took get interpreted in this regard?
Thanks as you can tell the worry is terrible even with your reassurances
Brief Answer:
You are safe. Relax
Detailed Answer:
hi.
yes, your recent tests are reliable specially considering the low/ negligible level of risk exposure.. If your risk exposure would have been high only then I would have considered more tests at 4 weeks and 12 weeks. P 24 antigen is detectable between 1-8 weeks after infection though it peaks at around 2-3 week mark. HIV RNA PCR too has a short window period of 9-13 days so considering that your P24 antigen (on 14 th day) and RNA PCR tests ( on 10 th day) are reliable. Moreover they are 2 different tests that came out negative, so that's doubly reassuring.
By sensitivity I mean, how many out of the total can a particular test pick up positive. So a test with 99% sensitivity is better than one with 95% sensitivity though it may pick up a few false positives.
By specificity I mean how many out of the total does a particular test rules out correctly i.e eliminates false positives. So a test which is 99% specific eliminates more false positives than a test which is 95% specific.
Regards
You are safe. Relax
Detailed Answer:
hi.
yes, your recent tests are reliable specially considering the low/ negligible level of risk exposure.. If your risk exposure would have been high only then I would have considered more tests at 4 weeks and 12 weeks. P 24 antigen is detectable between 1-8 weeks after infection though it peaks at around 2-3 week mark. HIV RNA PCR too has a short window period of 9-13 days so considering that your P24 antigen (on 14 th day) and RNA PCR tests ( on 10 th day) are reliable. Moreover they are 2 different tests that came out negative, so that's doubly reassuring.
By sensitivity I mean, how many out of the total can a particular test pick up positive. So a test with 99% sensitivity is better than one with 95% sensitivity though it may pick up a few false positives.
By specificity I mean how many out of the total does a particular test rules out correctly i.e eliminates false positives. So a test which is 99% specific eliminates more false positives than a test which is 95% specific.
Regards
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Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
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