HIV/Condom Research Question

[battier]

Hello Dr:

Thanks for the service you provide through this website.  Getting directly to my question, I understand from various medical articles that condoms are considered entirely effective against HIV assuming that they remain intact and do not break.  Usually, these articles reference a CDC study of 123 serodiscordant couples in which the HIV- partner never became infected with consistent condom use.  

However, I've also heard about update/later studies in which a very small sample of HIV- participants did report becoming infected even with consistent condom use (i.e. the 3% of 121 couples study for instance)

Now, I'm not asking this question out of any paranoia, but I'm just curious as to what could be the possible explanations for this since HIV obviously cannot go through a latex condom.  Would it be right to assume that since the couples probably self-reported their condom use, there is no real way to verify if in fact condoms were used for all acts of penetrative intercourse or that the condom never failed?  Thanks again.

[nycguy4]

I recently had vagainal intercourse with a prostitute while wearing a condom.  While no one will guarantee 100% effectiveness I had thought condoms were more or less 99.9% effective against HIV unless they break, slip, or are not worn properly.  In reading some articles however I read that that are 85% more effective than no protection, which shocked and awed me.  If the prostitute did have HIV but the condom was worn properly and did not break, is there still a possibility of transmitting HIV and if so what are the odds, 1 in 100, 1 in 10,000 ?

[H. Hunter Handsfield, M.D.]

For the reasons in my reply, even high quality scientific studies in peer reviewed journals cannot completely control for the vagaries of human behavior and self-reported condom use.

[txtony]

"However, I've also heard about update/later studies in which a very small sample of HIV- participants did report becoming infected even with consistent condom use (i.e. the 3% of 121 couples study for instance)" judging by your post, hearsay, compared to actual research as you indicate in your opening paragraph.
1) did you read that in a peer reviewed medical, or scientific article. if so, which one?
2) use of condoms properly and consistently, w/o breakage, is 100% effective protecting against hiv.

[battier]

TXTONY:

The link is: http://www.cdc.gov/mmwr/preview/mmwrhtml/00021321.htm.  This is just a blurb summary, but the endnotes include a reference to the study.  

I don't think the study was just "hearsay" or "non-scientific", but do think that the human factor (as Dr. H) suggested makes alot of sense as a good explanation.  

[H. Hunter Handsfield, M.D.]

Can I (or anyone else) prove that nobody, anywhere, ever caught HIV despite correct use of a condom that remained intact?  Of course not.  You can imagine scenarios with herpes or other wounds of the skin that were exposed to secretions; of the penis sliding loosely inside the condom, with secretions being massaged down to the tip; and that sort of thing.  That one can imagine such a thing, however, does not mean that it happens with measurable frequency, and the data support the conclusion that it does not--or at least that such events occur too rarely to measure or to worry about.

The important factor in your question is that people's histories of condom use (or histories of any health behavior you can think of) can be wrong.  In studies like you cite, it is much more likely that those who caught or transmitted HIV simply forgot some unprotected exposures (perhaps especially for sex in combination with alcohol or drugs); simply lied (which sometiems happens because research subjects believe the researcher expects or hopes for a particular answer, or because they are embarrassed to admit they didn't follow advice); forgot about one or more unprotected exposures; or were saving face by not admitting other exposures (e.g., extramarital sex, sex with men, injection drug use, etc).  If you think about it, this makes a lot of sense, and you probably can think of other situations that would lead a researcher to record false information.

I hope this helps.  Thanks for the thanks about the forum.  Best wishes--  HHH, MD