Tag Archive: transmission risk of HIV

Some interesting information on risk of HIV transmission

From: HIV Update <bulletins@bulletins.aidsmap.com>
Date: Thu, May 29, 2014 at 9:04 AM
Subject: Long-term HIV transmission risks – HIV update, 29 May 2014

Long-term HIV transmission risks

A group of American researchers have published an analysis which attempts to estimate the long-term risks of HIV being passed on within a couple.

This was a mathematical modelling study – in other words, it does not report new findings from a study of couples in the real world. Instead, modelling studies use previous research findings, assumptions and mathematical techniques to simulate a sequence of likely future events.

Their findings show that even if the risk of HIV being passed on during one sexual act is relatively small, the risk can accumulate over time for a couple who have sex regularly for a number of years.

The researchers wanted to get a rough idea of the long-term benefits and risks of using different methods to reduce the likelihood of HIV transmission. They were interested in couples where one person is HIV-positive and the other person HIV-negative, who were assumed to have penetrative sex six times a month.

For example, for an HIV-positive woman and HIV-negative man, who only have vaginal sex:

  • If no protective measures are taken, 6% risk of transmission after one year, which adds up to 44% after ten years.
  • If the negative partner takes pre-exposure prophylaxis (PrEP), 2% risk after one year, 15% after ten years.
  • If condoms are used, 1% risk after one year, 11% after ten years.
  • If the positive partner takes HIV treatment, 0.2% after one year, 2% after ten years.
  • If condoms and PrEP are used, 0.3% after one year, 3% after ten years.
  • If condoms and HIV treatment are used, 0.05% after one year, 0.5% after ten years.
  • If condoms and PrEP and HIV treatment are used, 0.01% after one year, 0.1% after ten years.

The risks are much greater for couples who practise anal sex, whether they are heterosexual or gay. (The risk of HIV transmission during receptive anal sex is 18 times greaterthan that during vaginal sex).

For a gay male couple:

  • If no protective measures are taken, 52% risk after one year, which adds up to 99.9% after ten years.
  • If the negative man takes PrEP, 34% risk after one year, 98% after ten years.
  • If condoms are used, 13% risk after one year, 76% after ten years.
  • If the positive man takes HIV treatment, 3% after one year, 25% after ten years.
  • If condoms and PrEP are used, 8% after one year, 59% after ten years.
  • If condoms and HIV treatment are used, 1% after one year, 6% after ten years.
  • If condoms and PrEP and HIV treatment are used, 0.3% after one year, 3% after ten years.

Some mathematical models that we have reported on in the past could be criticised for being based on unrealistically optimistic assumptions. This one can be criticised for including some rather pessimistic assumptions.

In particular, the estimates for pre-exposure prophylaxis (PrEP) and condoms assume that people who plan to use them don’t always manage to. Both PrEP and condoms are likely to be much more effective when they genuinely are used consistently.

The figures produced are rough estimates and there is much that scientists can debate. Nonetheless, the study brings to light four key points:

  • A small risk of transmission in a single act of sex translates into a much larger risk during a sexual relationship that lasts several years.
  • The risks of transmission through anal sex, especially in the long term, are much greater than through vaginal sex.
  • Current research shows that effective HIV treatment provides more protection than other strategies, including condoms.
  • The safest strategy is to use several prevention methods in combination, such as HIV treatment, PrEP and condoms.

Show us the real HIV transmission risks

Show us the real transmission risks

OPEN WIDE / Stop dumbing down HIV for gay men

Bill Coleman / Vancouver / Thursday, February 10, 2011

 

Gay men need to know the truth about HIV transmission.

I asked staff at a local AIDS agency why they don’t tell people the whole story about the risks of HIV transmission. The reply was something like, “Well, we thought about it but decided not to.”

I tried to get another local organization to provide this information on its website, but they declined.

What is going on here? Do people think we can’t handle the truth? How can we make informed decisions when we aren’t given the information we need to calculate the level of risk we’re each comfortable taking?

Can you answer this question accurately: how likely is it that an HIV-negative guy will get HIV if he is fucked in the ass by an HIV-positive guy not wearing a condom? Most people do not know the answer and will guess wrong. The risk is not as high as you might think.

When I used to lecture groups about HIV, I would ask this question. Many people thought there was a 100 or 90 percent chance that the negative guy would get infected. Some ventured to suggest a 50-50 chance of infection.

The truth is the risk is far lower! If you’re getting fucked in the ass by a positive guy, the chance of transmission is one time in 200, according to the US Centers for Disease Control.

The only local place I know of that will tell us these facts is on the Spectrum Health website. It is not easy to find but it is there (www.spectrum-health.net/index.php?option=com&mdashcontent&view=category&layout=blog&id=83&Itemid=200).

Here is the breakdown of sexual transmission risks for gay men, according to the US Centers for Disease Control:

•    being fucked by an HIV-positive     guy who cums inside you:     1 in 200

•    fucking an HIV-positive guy:     1 in 1,500

•    sucking an HIV-positive guy:     1 in 10,000

•    getting sucked by an HIV-positive         guy: 1 in 20,000

I’m not suggesting we all go out and take risks. I’m just saying we’re all entitled to make our own decisions about how many risks, if any, we want to take.

If you like to fuck and get fucked but do not like condoms much, then you can see it is seven times more risky to get fucked than to fuck without condoms.  Make your own choice about how much risk you are comfortable taking and how important the sex is for you.

I also think there would be less stigma for poz guys if we all knew the real risks of HIV transmission. Maybe then negative guys would find poz guys less scary. Living with constant fear of getting HIV can become a huge burden. Knowing the facts can help all of us to feel more in control and can help in making informed decisions around our sexual activities.

Other factors can affect the odds of getting HIV. High viral loads and sexually transmitted infections make transmission more likely, for example. Whereas an undetectable viral load makes it less likely. (Needless to say, avoiding getting cum in your ass makes transmission even less likely.)

Newly infected guys can have a high viral load for two months or more and be up to 20 times more likely to infect someone. I have concluded that it may be safer to have sex with a poz guy with an undetectable viral load than with someone who mistakenly thinks they are negative but really has a high viral load, which is what happens three to six months after infection.

A final rule of thumb to prevent HIV transmission: don’t get cum in your eyes. Getting blood in your eyes in a hospital setting is considered high risk.

Open Wide appears in every other issue of  Xtra