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HIV 4th generation ELISA


So a month and a half ago I had sex with a girl a barely know. We had vaginal intercourse and I used a condom all the time. I performed oral sex and she rubbed her genitals with mine (no condom in this case) so after that I got really scared and took a 4th generation ELISA (Ac. Anti VIH1 y 2/ Ag P24) at day 39 (0.18) NO REACTIVE and at day 50 (0.10) NO REACTIVE. So I want to know if theres a risk of contracting HIV through genital rubbing. I know there´s a chance of infection through oral sex but is close to zero, right? And I want to know how reliable are those tests. I want to take another test the 79th day, I know is the 84th day to be conclusive but I´m going to work on the countryside and I really can't take the test after the 79th day. Am really losing my mind over this. Does it chance a lot if the test is taken at 79 day and not at 84? Please, help me. I also read that the CDC says that after 6 weeks is conclusive right? And there´s no need for more testing.


Hi there, and thanks a lot for contacting the AIDS Vancouver Helpline for your HIV/AIDS related health information. It seems you have some questions regarding the risks involved in an encounter, and on the accuracy of some tests since then. We're happy to answer your questions for you.

Fist off, it's really great you decided to use a condom for your encounter, as condoms substantially reduce the risk of transmission of both HIV and other STIs. We'll now go through the risks involved in your encounter. Protected sex is considered a low risk activity, meaning that while transmissions are possible, they require specific circumstances to occur (like the condom breaking, for example). Giving oral sex is considered a negligible risk activity, meaning that while transmissions are theoretically possible, none have been documented to actually occur these ways. Rubbing is a no risk activity, as HIV does not transmit this way.

Here is a bit more information on the test you've had:

Test Name
Window Period
EIA (Enzyme Immunoassay) antibody 3rd Generation aka ELISA Blood test that looks for antibodies 4 weeks to 3 months (although up to 95% of infections are detectable within 4-6 weeks). Most people develop detectable antibodies in 21-25 days. Most commonly available testing method. We are encouraged to hear that 4th gen tests are on their way to Vancouver but currently are only available via referral. Accuracy is 99.8%

You'll see in the chart that this test is considered conclusive 3 months (or 90 days) post exposure. Remember that at most, your risk level was low risk, but in order to know your status conclusively after your encounter you'll need to wait until at least day 90. The 6 week CDC recommendation is actually for the DUO test, not the ELISA test, which is the test you've had. We normally recommend routine testing for all sexually active people, but you've already gone for a test (which is great). It's really up to you, however, if you want to know your status conclusively after this encounter. If you do, you need to wait until after at least day 90.

Thanks a lot for contacting the AIDS Vancouver Helpline with your questions. We hope they have been answered fully.


AIDS Vancouver Helpline/Online