Question 1: Is it true the CDC said the failure rate of condoms is 17% for heterosexual couples attempting to prevent pregnancy? Would the failure rate of condoms for couples attempting to prevent HIV transmission be higher than the failure rate of condoms to prevent pregnancy? Question 2: Dear Dr. S: I have been very worried about an encounter I had recently. It was protected sex with a female prostitute (I am male). The condom appeared to be latex and did not appear to leak or break. I understand that this encounter puts me at "very low risk," but my fear that I have contracted HIV remains. Even the NYC Dept of Health tells me that they would not advise me to have a test based on my encounter. That indicates to me that they calculate my risk to effectively be zero! I am looking for some hard facts to put things in perspective. What I would like to know is this: 1. What is the real effectiveness of condoms? Are there any reported cases of HIV transmission (female to male)during heterosexual sex with a properly used condom? Are there any scientific numbers which could give an idea of how effective this type of protection is? "Very Low" tells me very little! 2. Can HIV be transmitted through newly healed skin (such as a recently healed herpes sore)? Can the virus enter through the urethra by mere contact with the tip of the penis, or does there have to be some force, i.e. rough sex.? I realize these questions may seem hypochondriacal, but I am having a lot of trouble dealing with this and want to know as much as possible so I can get through this in a calm manner. Thank you for your time. ------------------------------------------------------------------------

Hi. Thank you for your questions.

When we calculate the failure rate for condoms, we look at the pregnancy rate per year that occurs in couples who use condoms. For latex condoms, the typical failure rate is about 12%. However, if condoms are used every time and used correctly every time , the failure rate falls to approximately 2 to 3%. Even when condoms are used perfectly, there is still a 2 to 3% failure rate, since condoms will sometimes break, even when used correctly. Nothing man-made works 100% of the time. However, most of the time condoms fail, is either because they're not used every time, or they're not used correctly. If a condom remains intact, and is used correctly, it will protect against both pregnancy and Sexually Transmitted Diseases (STD's) including HIV.

Several recent studies looked at couples in which one partner was infected with HIV, and the other wasn't (also known as discordant couples). One study looked at the infection rate of HIV-negative women having sex with HIV-positiv e men. In couples who did not use condoms every time, 12% of the women eventually became infected themselves. In couples who used condoms every time, less than 2% of the women became infected. In another study looking at positive persons having sex with negative persons, when condoms were not used every time, 10% of the negative partners ultimately became infected. In the couples who were always using condoms, none of the negative persons in the study became infected. These studies show that condoms will protect against HIV, but the key is that they be used consistently and correctly.

Failure rates can actually vary from one brand of condom to another. Consumer Reports magazine did a brand-by-brand comparison of condoms in their May 1995 issue, with an update in the January 1996 issue. This is perhaps the best review I've seen of failure rates for condoms. Because Consumer Reports does not accept any advertising, they were able to be totally objective at rating one brand of condom versus another. Consumer Reports is available at most libraries, and is also available through several online services, including America Online, CompuServe, Dialog, Nexis and Prodigy.

As long as condoms are used consistently and correctly, they will significantly reduce (but not eliminate) the risk for pregnancy and Sexually Transmitted Diseases (STD's). But they will never be 100% protection, but they can significantly reduce one's risk. As long as a condom remains intact, and does not leak or fall off, a person would be protected against pregnancy and STD's.

If a man does not use a condom, HIV can enter his bloodstream through microscopic cuts and abrasions that normally occur on the head of the penis. These microscopic openings are a result of the normal friction that normally occurs during intercourse, and are too small to visually see, but large enough for HIV to enter. These small cuts/abrasions are most likely to occur on the head of the penis, since this is made of mucous membranes, which tend to abrade easier than regular skin. Also, if a man were to have any open lesions due to other STD's (like herpes, syphilis etc.), it would be much easier for HIV to enter his bloodstream.

So in summary, condoms used consistently and correctly will significantly reduce one's risk of pregnancy and STD's. If they remain intact, they act as excellent barriers against pregnancy and infections. But the key to their success is that they be used every time, and used correctly.

If you have any further questions, please feel free to contact the Centers for Disease Control at 1.800.232.4636 (Nationwide).