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Is the pcr negative hiv test conclusive 12 days after possible exposure?

Possible exposure incident was in dec 26 2019, we both took elisa test 2 days later since we hadnt only known each other for less than a week and were both negative. I took a pcr test again 12 days after incident and it came back negative. Is that conclusive?
2 Responses
3191940 tn?1447268717
COMMUNITY LEADER
What was your possible exposure?

The PCR test is not considered a primary diagnostic test.  A 4th or 5th generation Ag/Ab test is recommended 28 days (or more) post-exposure.  If not available, an antibody-only test will be conclusive at 90 days post-exposure.
4 Comments
Vaginal penetration and i am a guy. I was under impression that pcr is the most accurate test and can be done as soon as 3 days, a friend also claimed that its what they use to screen donated blood in the intrest of time.

Is Elisa test also 4th or 5th generation Ag/Ab test?
Elisa is a method, not a specific test.  You would have to ask your testing center.  PCR can be used to screen blood, but again, it is NOT a test intended for diagnosis.  It is a follow-up test after a positive antigen and/or antibody test.
This comment is confusing in many ways,  all i want to know is if the pcr can detect hiv 12 days after exposure, then u say its not used for diagnosis but it can be used to screen blood. The point is could it be negative after 12 days but be positive at anypoint afterwards? Other platform say it can be used to screen babies born to positive mothers, is that not diagnostic use? Is the fact that my pcr was negative significant or insignificant?
Yes, it *can* detect the presence of the virus  at 12 days, and yes, it could be negative at 12 days and positive at some point afterward.  

I don't know anything about newborn or blood screening.  This forum's advice is derived from the recommendations of expert HIV physicians and scientists.
188761 tn?1584567620
COMMUNITY LEADER
Since PCR tests are very sensitive and directly looks for the viral genome. A PCR RNA, theoretically can be used to determine infection as early as 72 hours post transmission. However, as stated by CurfewX, it is not a recommended test for primary diagnostic purpose.

I am assuming that you have taken an RNA PCR and not a DNA PCR at 12 days because RNA PCR is the test that is recommended to be best taken at 10-14 days, if someone has an exposure with a known positive partner.

Since the viral replication post transmission is high and PCR RNA looks for the infected RNA with sensitivity of as low as 20-50 copies, the chances of missing an infection is substantially low.

Your risk was low, plus an undetected RNA NAT only suggests you weren't infected from your event. As suggested by CurfewX, you will have to back this result up with a standard antibody test, that's the testing protocol. Timelines for testing is already provided to you.
1 Comments
Great stuff. Thank you kindly.
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