The ideal and the real in HIV prevention

“Mass screening of all AIDS sufferers could wipe out the disease within 40 years,” was the Daily Mail’s headline regarding the most widely reported speech at the recent Conference on Retroviruses and Opportunistic Infections. If we could put the vast majority of HIV-positive people in the world on antiretroviral drugs (ARVs), that is.

The World Health Organization’s Brian Williams in fact went further in his claim. “I believe if we used antiretroviral drugs we could effectively stop transmission of HIV within five years,” he said.¹

Scientifically, this makes sense. If you reduce a person’s viral load, they will become a lot less infectious.

The Partners in Prevention study of long-term couples of different HIV status found that putting the positive partner on HIV therapy reduced the chances of HIV transmission by 92%. That’s better than the rate achieved when people try to use condoms all the time (typically 80 to 85%).

Putting everyone on treatment feels like a simple answer to an infection that has shrugged off complex ones like vaccines. Maybe the answer was staring us in the face all along, and treating more people with HIV may indeed, in the long run, become an important part of stopping the HIV pandemic.

But there are four different reasons why it won’t happen overnight.

Firstly, the reduction in transmissions seen in Partners in Prevention won’t necessarily apply to everyone. This was a group of long-term heterosexual couples, primarily monogamous. They had low levels of sexually transmitted infections (STIs) and casual sex, and most sex was vaginal. A tougher test of ARVs would be to see if they can reduce infections in gay men who have unprotected anal sex, high numbers of partners and high levels of STIs.

Secondly, over the next few years the world will find it hard enough to treat the people who are in imminent danger of death, let alone put everyone on therapy. In one study from South Africa, the country’s twentyfold expansion of therapy in the last four years did not prevent a quarter of people on the waiting list for drugs dying before they got a single pill. While such urgent needs aren’t being met, is it realistic to talk of putting everyone on therapy?

Thirdly, using HIV therapy as a public health measure will not work if it rides roughshod over people’s fears of being identified as HIV-positive and stigmatised in their communities. A poster from Uganda² echoed something that’s been seen amongst gay men in the global north: the more likely people are to have HIV, the more likely they are to avoid testing. These will be exactly the people testing drives miss. Treatment as prevention simply won’t work unless programmes are put in place to address the stigma of HIV before the testing caravan rolls into town.

Lastly, making a real dent in incidence by means of treatment is simply a very, very hard thing to do.

It is possible. One of the most hopeful studies presented at the conference was from San Francisco. It showed that very high rates of testing and treatment may be starting to bring the rate of new infections down, due to what may be the world’s highest HIV testing rates. Only one in seven San Franciscans with HIV doesn’t know it.

But HIV incidence and prevalence only improve slowly with increases in testing and treatment. A high proportion of infections (maybe a third) are spread by very recently infected people who haven’t been diagnosed. And the sum total of people with HIV won’t decline fast because HIV-positive people are staying alive to be counted.

Even with rates this high, only a minority of the HIV-positive population may have an undetectable viral load. In San Francisco 85.5% of people with HIV are now diagnosed; 78% of these get linked to care; 90% of these take ARVs; and of these, 72% become virally undetectable.

Do the sums: even with such high testing and coverage rates, only 43% of San Franciscans with HIV have an undetectable viral load.

Treatment as prevention will need to be truly universal to work.

That doesn’t mean it’s not worth trying. We need radical answers if HIV prevalence is not going to spiral ever upwards as people live longer on treatment. Brian Williams said “the only thing that’s going to be more expensive than this is not doing it”.

In the long run, it may be better for anyone with HIV to be on the drugs than not. Yes, side-effects may wait along the line as we get older, but so will the long-term effects of having HIV, which are probably worse.

In the end, treatment as prevention and optimal HIV treatment may amount to the same thing.