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Oral test accuracy at six weeks
Hi Drs. Today I did an in-home Oraquick test using oral fluids. It was negative. It is a day short of six weeks after a potential exposure (i.e., it was 41 days ago). The exposure was heterosexual sex with a female commercial sex worker. I wore a condom before, during, and after. It seemed to be intact when I checked it afterwards, meaning that it wasn't torn and didn't have any holes in it.
1. How reliable is this ~6 week result using a rapid test based on oral fluids? I've read recent responses from both of you talking about new, unpublished research suggesting that the oral fluids rapid tests take longer to detect antibodies.
2. I also had oral fluids rapid tests at the 4 and 5 week marks, both of which were also negative.
3. Can I consider this result "good enough" to conclude, medically speaking, that I'm not infected and can therefore be in a position to move on from this experience, including having unprotected sex with my longterm girlfriend?
4. I've read your risk assessments for many, many, many other guys in my situation and there's often a statement about the likelihood of a csw having HIV being very low, etc. However doesn't the prevalence vary depending on country of origin of the csw? I've seen at least one academic study on that (Baral et al. 2012, The Lancet Infectious Diseases). The csw I encountered was from Ukraine, which has a higher prevalence for female sex workers than average (based on the limited scholarly research out there). Anyway, it is probably splitting hairs, but I'm wondering more generally what you think about the variance in HIV prevalence for csws by country of origin? (Maybe this is a bit too general a question...sorry if that's the case).
Thanks in advance for your answers to my questions, and thanks more generally for what you both do on here. It is truly impressive!
1. How reliable is this ~6 week result using a rapid test based on oral fluids? I've read recent responses from both of you talking about new, unpublished research suggesting that the oral fluids rapid tests take longer to detect antibodies.
2. I also had oral fluids rapid tests at the 4 and 5 week marks, both of which were also negative.
3. Can I consider this result "good enough" to conclude, medically speaking, that I'm not infected and can therefore be in a position to move on from this experience, including having unprotected sex with my longterm girlfriend?
4. I've read your risk assessments for many, many, many other guys in my situation and there's often a statement about the likelihood of a csw having HIV being very low, etc. However doesn't the prevalence vary depending on country of origin of the csw? I've seen at least one academic study on that (Baral et al. 2012, The Lancet Infectious Diseases). The csw I encountered was from Ukraine, which has a higher prevalence for female sex workers than average (based on the limited scholarly research out there). Anyway, it is probably splitting hairs, but I'm wondering more generally what you think about the variance in HIV prevalence for csws by country of origin? (Maybe this is a bit too general a question...sorry if that's the case).
Thanks in advance for your answers to my questions, and thanks more generally for what you both do on here. It is truly impressive!
MEDICAL PROFESSIONAL
It isn't plausible that 15% of all sex workers in Ukraine have HIV. Most studies of STDs and HIV in sex workers are highly biased, typcially toward those at highest risk.
"I assume no further testing is recommended in medical grounds?" Correct -- only for reassurance if you feel you need it.
"I assume no further testing is recommended in medical grounds?" Correct -- only for reassurance if you feel you need it.
Thanks for your quick reply. This is helpful and informative. I think the article I cited put prevalence of Ukranian csws at about 15% on average. I assume that doesn't alter your risk assessment since there was a condom.
That being the case, I assume no further testing is recommended in medical grounds? Thanks again for your advice.
That being the case, I assume no further testing is recommended in medical grounds? Thanks again for your advice.
MEDICAL PROFESSIONAL
Welcome to the forum. Thanks for your question. Thanks for esearching your question ahead of time.
You describe an essentially zero risk exposure for HIV (and other STDs): it is statistically unlikely your CSW partner had HIV; transmission by vaginal sex is rare after a single exposure, even if the female is infected; and because you had entirely safe sex including, with a properly used condom that didn't break. To your specific questions:
1,2) The oral fluids test is the least accurate for early testing. I only recommend it for people who are worried about long-term HIV infections (3 months or more), and that it be avoided if concerned about a specific recent exposure. Although all the antibody blood tests almost always are positive within 6 weeks, it probably takes about 3 months for definitive results with the OF test. Your 6 weeks result probably is about 90% reliable.
3) Since your risk of catching HIV was almost zero, from a medical standpoint you don't need further testing. Look at it this way: even before you were tested, I would put your risk of having caught HIV at well under 1 in a million. With a 90% reliable test, that makes the chance 1 in 10 million. I hope you'll agree that's zero for all practical purposes.
4) I'm sure you're right that the chance a sex worker has HIV varies with national origin, and certainly heterosexually transmitted HIV is a lot more common in Ukraine than in the US or western Europe. On the other hand, if she is a legal immigrant to N. America, she probably was HIV tested before arrival. And even if some nationalities residing in the US still have higher HIV risks than others, we're talking about pretty minor differences. Consider my analysis above: my answer would be no different if we judged your partner as having a 1 in 100, 1 in 1,000, or 1 in 10 thousand risk of having HIV.
So you really needn't be worried and don't need further testing. However, if you can't live with the fact that the test itself is "only" around 90% reliable, then you need another OF test at 3 months; or a blood test at any time.
I hope this has helped. Thanks for your kinds words about our services.
HHH, MD
You describe an essentially zero risk exposure for HIV (and other STDs): it is statistically unlikely your CSW partner had HIV; transmission by vaginal sex is rare after a single exposure, even if the female is infected; and because you had entirely safe sex including, with a properly used condom that didn't break. To your specific questions:
1,2) The oral fluids test is the least accurate for early testing. I only recommend it for people who are worried about long-term HIV infections (3 months or more), and that it be avoided if concerned about a specific recent exposure. Although all the antibody blood tests almost always are positive within 6 weeks, it probably takes about 3 months for definitive results with the OF test. Your 6 weeks result probably is about 90% reliable.
3) Since your risk of catching HIV was almost zero, from a medical standpoint you don't need further testing. Look at it this way: even before you were tested, I would put your risk of having caught HIV at well under 1 in a million. With a 90% reliable test, that makes the chance 1 in 10 million. I hope you'll agree that's zero for all practical purposes.
4) I'm sure you're right that the chance a sex worker has HIV varies with national origin, and certainly heterosexually transmitted HIV is a lot more common in Ukraine than in the US or western Europe. On the other hand, if she is a legal immigrant to N. America, she probably was HIV tested before arrival. And even if some nationalities residing in the US still have higher HIV risks than others, we're talking about pretty minor differences. Consider my analysis above: my answer would be no different if we judged your partner as having a 1 in 100, 1 in 1,000, or 1 in 10 thousand risk of having HIV.
So you really needn't be worried and don't need further testing. However, if you can't live with the fact that the test itself is "only" around 90% reliable, then you need another OF test at 3 months; or a blood test at any time.
I hope this has helped. Thanks for your kinds words about our services.
HHH, MD
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