The possibilities for new and improved HIV prevention options were showcased at the recent HIV Research for Prevention (HIVR4P) conference, although the participants heard that many new tools are still several years from being ready for implementation.
The importance of pre-exposure prophylaxis (PrEP), including PrEP delivered by a vaginal ring and long-acting PrEP, including injectable PrEP, was featured in many presentations. Vaginal ring PrEP offers better female-controlled prevention options that can protect women without their partner’s knowledge, while injectable PrEP would mean that daily pill-taking and the risk of forgetting to take the pill would be history. Both vaginal ring PrEP and long-acting PrEP are still some way from being available, however, with the vaginal ring currently being reviewed for regulatory approval by the European Medicines Agency and trials for long-acting PrEP not due to deliver results until 2021 or later.
If antibodies and engineered molecules that mimic them can be shown to prevent HIV infection, the way to six-monthly injections for either prevention or treatment could be opened up, along with the possibility of a vaccine that made people develop their own similar antibodies. The participants heard that much progress had been made in discovering and developing such antibodies. The first proof of principle trials showing their effectiveness will report their results in 2020.
“Science has delivered us extraordinary advances in technologies for the diagnosis, treatment and monitoring of HIV infection. There is now real excitement that over the next years it will also lead to effective affordable prevention tools,” said Peter Godfrey-Faussett, Science Adviser, UNAIDS.
The participants heard that there are high levels of sexually transmitted infections (STIs) among the populations at higher risk of HIV and that, as we have known for decades, STIs lead to increased HIV acquisition. The rates of the major treatable bacterial STIs have been rising steadily and are at alarming levels among gay men and other men who have sex with men and young people in eastern and southern Africa, in part due to declining condom usage. The high rates of the major treatable STIs have become particularly evident with the advent of increased screening accompanying the roll-out of PrEP.
Many STIs have no symptoms and can only be diagnosed with modern diagnostic tests—these are simple, but still far too expensive for the countries that need them the most. Along with geography and age group, STIs are among the strongest indicator of risk of HIV. An integrated STI and HIV prevention approach could offer PrEP to people who are HIV-negative but have an STI and live in an area where HIV is prevalent.
New prevention technologies are likely to be relatively expensive and hence will need to be focused on populations at higher risk in order to be affordable and cost-effective. Mathematical modelling shows that these new HIV prevention technologies may have only a limited impact on new HIV infections in eastern and southern Africa. For example, modelling of the impact of the dapivirine ring—a vaginal ring with a slow release of an antiretroviral medicine that protects against HIV infection—shows that only 1.5–2.5% of HIV infections would be averted over the next 18 years in Kenya, Uganda, Zimbabwe and South Africa. With the cost of averting one HIV infection through the use of the dapivirine ring varying from US$ 10 000 to US$ 100 000, many of the participants argued for integrating and combining both HIV treatment and prevention, and the responses to HIV and other diseases, for maximum effect.
The biennial HIVR4P conference was held in Madrid, Spain, from 21 to 25 October.
