Condoms and viral load

A new condom campaign produced by Terrence Higgins Trust is running right now, maybe you've seen the ads online or in the gay press: Clever Dick / Smart Arse. If you go to the web site www.clever-dick.org you can have your sex life scored in a survey that looks at your risk of passing HIV on.

One of the survey questions asks about sex without a condom if you're on HIV treatment with an undetectable viral load. The likelihood of HIV being passed on in these circumstances is a much talked about issue. In the survey it’s not given a 'low risk' rating. Let’s look at the thinking behind that.

It's been established through various studies that being on treatment significantly lowers the risk of HIV being passed on, especially if viral load is kept undetectable for at least six months and medication is being taken properly. These studies looked at monogamous straight couples who were free of STIs; only vaginal sex was studied. In some cases the reduction in the risk of HIV transmission was 96% (a figure not much below the success rate of condoms when used correctly). A few experts have gone as far to say that people with undetectable viral load are essentially no longer infectious, although many others disagree.

Many questions remain. Can results from studies on monogamous straight couples be translated to gay men, especially those having casual sex partners? The balance of evidence is that, even with undetectable viral load, anal sex is still more likely to transmit HIV than vaginal sex. And if a man is not in a monogamous relationship there's the chance he may have an undiagnosed sexually transmitted infection (or pick one up at some time): such infections are known to push HIV viral load up. Could this upward blip in viral load still happen when someone is taking HIV meds? There’s also the difference between having undetectable levels of virus in your blood (as measured by viral load tests) and what’s in your semen. Studies have shown that it’s possible to have a higher level of HIV in your semen than in your blood. In in 20 gay men in one study who were undetectable in the blood had detectable virus in their semen.

Although being 'undetectable' means a significantly lower risk, there are a small number of documented cases of gay men being infected by partners who were 'undetectable'. So to be safe condoms are still the best option. Checkups for sexually transmitted infections at least once every six months will pick up any undiagnosed infections that could push up viral load and make HIV transmission easier.

You can get confidential advice on any aspect of HIV by calling THT Direct on 0808 802 1221 or by emailing info@tht.org.uk.