Although the underlying ideas and messages in this article remain relevant, much HIV prevention research has been published since , notably about there being effectively no risk of transmitting the virus if you are HIV positive and undetectable a. Can you get HIV from oral sex? Americans really want to know their HIV risk during fellatio—even more so than during anal sex. Sure, you can Google the subject, but the results may further confuse and scare you.
Numbers seem less abstract, more specific. But do they give us a better understanding of HIV risk and sexual health? Probabilities of HIV transmission per exposure to the virus are usually expressed in percentages or as odds see chart at the end of this article.
For example, the average risk of contracting HIV through sharing a needle one time with an HIV-positive drug user is 0. The risk from giving a blowjob to an HIV-positive man not on treatment is at most 1 in 2, or 0.
The risk of contracting HIV during vaginal penetration, for a woman in the United States, is 1 per 1, exposures or 0. As for anal sex, the most risky sex act in terms of HIV transmission, if an HIV-negative top—the insertive partner—and an HIV-positive bottom have unprotected sex, the chances of the top contracting the virus from a single encounter are 1 in or 0.
Specifically, it is 1. If the guy pulls out before ejaculation, then the odds are 1 out of Is HIV really this hard to transmit, especially in light of the alarming statistics we are bombarded with?
Although the CDC estimates that nearly 1. And before you even think it: No, the answer is not that everyone with HIV is a ginormous slut who has never heard of safer sex. Liz Defrain For starters, you have to understand that these probabilities of HIV transmission per single exposure are averages. They are general ballpark figures that do not reflect the many factors that can raise and lower risk. One such factor is acute infection, the period of six to 12 weeks after contracting the virus.
So right there, the per-act risk of receptive vaginal transmission jumps from 1 out of 1, exposures to 1 out of 50 exposures, and the risk of receptive anal sex goes from 1 out of 70 to higher than 1 out of 3. Vaginal conditions such as bacterial vaginosis, dryness and menstruation also alter risk. But they can be a good tool for understanding risk.
Other factors lower risk. Circumcision does so an average of 60 percent for heterosexual men. HIV-negative people can take a daily Truvada pill as pre-exposure prophylaxis, or PrEP, to lower their risk by 92 percent; similarly, there is post-exposure prophylaxis, or PEP.
And the CDC says condoms lower risk about 80 percent. Of course, these numbers will vary based on correct and consistent use of the prevention strategy. Researchers also view risk through the constructs of family, relationships, community and socioeconomic status. Then there is the concept of cumulative risk. The oft-cited numbers for the risk of HIV transmission take into account one instance of exposure.
But this is not a static number. Doing so is a serious gamble. Numbers and probabilities can be miscalculated and misinterpreted. Having a 1 in 70 chance of transmitting HIV does not mean it takes 70 exposures to the virus in order to seroconvert. It simply means that out of 70 exposures, on average, one will lead to HIV; bad luck might have it that the transmission occurs on the very first exposure. Another important concept to grasp is absolute risk what the risk actually is versus relative risk the percent change in the risk.
In this example, a 92 percent risk reduction does not mean the final absolute risk is 8 percent. Instead, it is a 92 percent reduction of the beginning risk.
If the beginning absolute risk is 50 percent, then PrEP reduces the risk to 4 percent; if the beginning risk is 20 percent, then PrEP lowers it to 1. Also, there are often research gaps, he says, meaning that in many cases, scientists might not yet have real-world examples to back up these numbers and calculations, but they do have mathematical modeling and the biological rationale for why certain ideas about HIV risk are true. And for a great primer on understanding health statistics, get your hands on a copy of Know Your Chances: During sex, our risk perception is replaced by love, lust, trust and intimacy.
Surveys have found that more than one in five gay men in urban cities are HIV positive, and the virus is more prevalent among MSM of color and certain communities.
People in these communities are more likely to come in contact with the virus even if they have fewer partners and practice safer sex more often. Perhaps the biggest miscalculation is the incorrect assessment that you or your partner is HIV negative.
But a young guy from the Midwest who looks negative? Liz Defrain Data be damned. Often for good reason. One survey asked young MSM who cruised for sex online to list their main worries. And in the real world, risk-takers are celebrated. We have to take risks every day. Sexual health is often framed in the idea of risk instead of rewards.
This may present HIV and those living with it as the worst possible outcome imaginable, he notes, which is not only stigmatizing but often irrational and false since many people with HIV are, in fact, just fine. Click here to download a copy as a PDF.