Three Cheers For HIV Treatment, Only One For Prevention

The news that treating HIV early can significantly reduce transmission in discordant couples, where only one partner is positive, is very good indeed. It should provide some impetus for increasing considerably the number of people receiving treatment, and at an earlier stage of disease progression. This should give a high level of protection to people with HIV positive partners, if the 96% protection in the trial is anything to go by.

It remains to be seen whether funding for the number of people currently on treatment will be doubled, especially as the costs of treatment go way beyond the costs of antiretroviral drugs, which have attracted much of the funding so far. And many donors are reluctant to even keep funding at its current levels.

But the same research shows that treating HIV is not enough to prevent transmission to the extent that it can be completely eradicated in the forseeable future. Among the 39 new HIV infections in the study, only about 70% were clearly transmitted by the HIV positive partner. The others were either transmitted by a different partner, or perhaps were transmitted non-sexually.

In addition, in some countries, a very high percentage of new HIV infections occur in stable relationships. But many of these infections occur where neither partner was previously infected. This is what gives rise to concurrency in the first place. But it is not always clear how or why some people are infected when their partner is not.

Of course, some instances may be simply a matter of one partner either having a sexual relationship with someone who is not their partner or being infected in some other way. But other instances are not so easily explained away. In some countries, about half of these occurrences involve women being infected, but not by their partner, the other half men.

Anyone can speculate about the sexual behavior of people who become infected, but many years of studies in many countries involving tens of thousands of people show that HIV transmission is not very closely correlated with sexual behavior that is considered to carry a high risk of HIV infection.

Often, those who use condoms the most, have the fewest sexual partners (sometimes none at all), have the fewest 'risky' sexual experiences and know all they need to know about 'safe' sex appear to be the most likely to be HIV positive. While certain people are being infected sexually, it is by no means clear that this is the main route of infection in other groups.

So HIV treatment is vital for HIV positive people and it may also prevent infection in some scenarios. But it is by no means enough to ensure that HIV transmission levels are lowered to a position where HIV will become a thing of the past. The very fact that so many people are still being infected years after antiretrovirals have been available to millions of people shows that prevention needs to include more than just treating greater numbers of people and treating them earlier.

And not really knowing how most people became infected in the first place is a big gap in our understanding. There is quite an absurdity in thinking that we can make a serious dent in the worst HIV epidemics when we don't really know why so many people are becoming infected, apparently sexually, with a virus that is relatively difficult to transmit sexually.

The news is good for HIV negative people in discordant relationships, but not for HIV negative people who are not in discordant relationships. And while HIV positive people need treatment, many might still question how they became infected in the first place when their partner is not infected. Prevention has received very little attention so far, so let's not allow the scaling up of treatment to deflect attention even further.