Revisiting Undetectable
February 27th, 2009
When viral load testing became part of HIV care in BC a number of years ago, many mistakenly thought that an “undetectable” result meant that they no longer had HIV (best case scenario) or at least weren’t infectious anymore. Sadly, what we knew then indicated it wasn’t true. But in the past year, the question of undetectable viral load and infectiousness has come up again, largely sparked by what’s come to be known as the “Swiss Statement.”
Undetectable is a potentially confusing term. In viral load testing, HIV levels are measured in the blood. A test result of “undetectable” doesn’t mean that HIV is gone from the blood (and even if it were, we know that HIV remains in tissue throughout the body). It means that the level of virus in the blood is below the level of measurement. In other words, if the viral load test is measuring for 40 copies of HIV per milliliter of blood, and there are fewer than 40 copies, that viral load result will be considered “undetectable,” but HIV is still present. It’s like being weighed to see if you are less than one hundred and thirty pounds- if you are, it doesn’t mean you disappear.
The Swiss Statement was issued by four physicians in January 2008, and hit the HIV world like a storm. Here’s the summary (note the emphases): IF a positive person is strictly adherent to antiretroviral therapy and IF their viral load has been undetectable for six months or more and IF they are free of any sexually transmitted infections, the likelihood of them infecting a partner sexually through vaginal intercourse was very low. So low that monogamous heterosexual partners who fit the scenarios could consider ditching condoms for vaginal intercourse (only) without too much worry. It went on with a couple more cautions, and to emphasize that new sex partners should use condoms.
Several months after the Swiss statement, Australasian researchers released findings that looked at what the “very low” level of risk might mean long term. Using a mathematical model of a hypothetical ten years of unprotected sex between the “ideal” candidates from the Swiss Statement guidelines, they found there would be an increase in new infections as compared to ten years of the same couples continuing to use condoms. To his credit, at AIDS 2008, one of the authors said it was not imagined that it would be applied to everyone (it’s hard to keep something like this under wraps, though).
So there’s reason for optimism (lower infectiousness) and reason for sex partners to talk (assessing infectiousness), both good things. But how do you actually apply the statement to your sex life? The statement recommends that everyone with new partners use safe sex practices. This leaves the long term monogamous couples. But even for monogamous heterosexual partners, every sexual encounter could have different factors you’re not aware of (a yeast infection can throw balance off). Vaginal sex and anal sex have different levels of risk (and anal sex isn’t just limited to sex between men).
People make decisions about varying levels of sexual risk all the time, and the Swiss Statement has widened the understanding of risk and of HIV treatment’s potential. Maybe for some people it’s too early to forgo condoms, and for others it’s about time… occasionally. The best case scenario is that both sex partners have access to complete information about each other. Seeing as that’s not always possible, don’t forget your safer sex info.
- Janet (with thanks to Oak Tree Clinic Researcher Evelyn Maan, who talked about the Swiss Statement in the drop-in the other day).
This blog represents the ideas of individual writers, and does not necessarily reflect any formal stance taken by Positive Women's Network.
This was posted on Friday, February 27th, 2009 at 10:01 am and is filed under Education & Resources, HIV Prevention, HIV Treatment . Feel free to respond, or trackback.
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