One of the hopes is that those selling pre-exposure prophylaxis (PrEP) will be able to ‘target’ people thought to be most at risk of being infected. However, there is little point in targeting those who are not at risk, or even those who don’t believe they are at risk. Pre-exposure prophylaxis doesn’t work if people don’t take it frequently enough, and those who don’t believe they face any risk are unlikely to take it at all.
A scatter-gun approach would be very expensive and wouldn’t be very effective. But an approach that ‘targets’ people merely on the basis that they are sexually active is in danger of becoming a scatter-gun approach. So, on the one hand, this study (like many others) shows that most people don’t engage in the kinds of behavior said to carry a high risk of HIV infection (and many who do engage in them remain HIV negative).
But on the other hand, this study fails to acknowledge that the assumption that all risk is, directly or directly, related to sexual risk, is completely unwarranted. It is concluded that PrEP can be ‘targeted’ at women who are at risk, but that more work will need to be done to convince these women that they are at risk, and that that risk is either directly or indirectly sexual. (There’s a favorable commentary on the article on AidsMap.com).
Another study takes up the question of whether most transmission is sexual and, therefore, whether most risk is in some sense sexual risk. It does so by considering similarities among HIV genetic sequences, in order to identify possible sexual links. This study finds that only a small minority of clusters of sequences have identifiable sexual links.
This study goes on to note that there is plenty of useful data available: tens of thousands of people in African countries were followed and thousands of new infections were observed among them, but less than 10% of these were attributable to sexual transmission; also, there have been numerous HIV outbreaks outside of Africa which have been a result of unsafe healthcare (all are documented on this site). Yet, none have been investigated in Africa.
This is not such good news for PrEP, because non-sexually transmitted HIV is likely to be better addressed in other ways. But it could be great news for people in high prevalence countries. Sexual behavior and its determinants are notoriously difficult to influence, but conditions in healthcare facilities should prove more tractable. In addition, people need to be made aware of the non-sexual HIV risks so that they can avoid them, at least until conditions in healthcare facilities are improved.