Aa
Testing
Hi doctor -
Quick question, is there any difference in me using a 2nd gen vs 4th generation test 4 months post exposure and 3 months post PEP? I know 4th is more current, but is there or could there an actual difference at this point? Thank you.
Quick question, is there any difference in me using a 2nd gen vs 4th generation test 4 months post exposure and 3 months post PEP? I know 4th is more current, but is there or could there an actual difference at this point? Thank you.
MEDICAL PROFESSIONAL
Oops. I forgot that the thread on PEP was deleted; the user was banned from MedHelp because he had abused his privileges. Here is the main part of my response before it was deleted:
"There are no data on the extent to which PEP, if it fails, may result in delayed seroconversion to positive antibody test results. Most experts believe that a negative test at 3 months remains highly reliable, probably 100%. However, because of the uncertainty, some experts recommend a final test at 6 months.
"It's all educated guesswork; there has been no systematic research, and so few people have actually acquired HIV after PEP that even reviewing patient health records provides no useful data. In fact, this is one reason that PEP should not be taken lightly, and should be limited to situations in which the risk of infection is substantial. In "worried well" persons following low risk exposures, the main effect of PEP probably is to prolong the anxiety."
"There are no data on the extent to which PEP, if it fails, may result in delayed seroconversion to positive antibody test results. Most experts believe that a negative test at 3 months remains highly reliable, probably 100%. However, because of the uncertainty, some experts recommend a final test at 6 months.
"It's all educated guesswork; there has been no systematic research, and so few people have actually acquired HIV after PEP that even reviewing patient health records provides no useful data. In fact, this is one reason that PEP should not be taken lightly, and should be limited to situations in which the risk of infection is substantial. In "worried well" persons following low risk exposures, the main effect of PEP probably is to prolong the anxiety."
MEDICAL PROFESSIONAL
Welcome to the forum and thanks for your question.
Two recent threads went into detail about time to positive results with various tests and the potential effect of PEP on test timing (about which little is known). Third generation antibody tests reliably become positive sooner (almost always by 6 weeks) than second generation (usually by 8 weeks). Fourth generation isn't really a new test, but the combination of 3rd gen antibody plus a test for p24 antigen. Without PEP, 4th gen is always positive by 4 weeks. PEP probably doesn't have much effect, but has not really been studied and so for an extra measure of safety, most experts would recommend testing later than otherwise, perhaps as long as 3-6 months after exposure.
Your test results are probably 100% proof you weren't infected, but because of the PEP your doctor might want you to have a final test, maybe 6 months after exposure.
Here are links to the other threads with more detailed information:
http://www.medhelp.org/posts/HIV-Prevention/what-is-the-window-period-for-hiv/show/1704700
http://www.medhelp.org/posts/HIV-Prevention/PEP-Delayed-Seroconversion-Testing/show/1708665
I hope this has helped. Best wishes
Two recent threads went into detail about time to positive results with various tests and the potential effect of PEP on test timing (about which little is known). Third generation antibody tests reliably become positive sooner (almost always by 6 weeks) than second generation (usually by 8 weeks). Fourth generation isn't really a new test, but the combination of 3rd gen antibody plus a test for p24 antigen. Without PEP, 4th gen is always positive by 4 weeks. PEP probably doesn't have much effect, but has not really been studied and so for an extra measure of safety, most experts would recommend testing later than otherwise, perhaps as long as 3-6 months after exposure.
Your test results are probably 100% proof you weren't infected, but because of the PEP your doctor might want you to have a final test, maybe 6 months after exposure.
Here are links to the other threads with more detailed information:
http://www.medhelp.org/posts/HIV-Prevention/what-is-the-window-period-for-hiv/show/1704700
http://www.medhelp.org/posts/HIV-Prevention/PEP-Delayed-Seroconversion-Testing/show/1708665
I hope this has helped. Best wishes
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