The latest UNAIDS statistics on HIV show that in the past 12 months an extra 2 million people have accessed HIV treatment: 17 million of the near 37 million infected are now receiving potentially life-saving antiretroviral drugs. As the proportion of people on treatment moves closer to 50%, the beneficial effects are already moving beyond viral suppression among those people with the virus to prevention of new infections, because people living with HIV who are on effective therapy are unlikely to pass on the infection. However, the 2020 target of 90-90-90 is still some way off, and the number of new infections each year remains stubbornly around 2 million worldwide, and in some priority high-risk groups and in some regions the growth in the number of new infections and the evolution of the epidemic is a cause for serious concern. So although the gains in treatment are most definitely to be applauded, prevention must not get left behind.
With this in mind, the July issue of The Lancet HIV is dedicated to prevention in a series of papers initiated by researchers at the Bill & Melinda Gates Foundation. For many readers the Article by Garnett and colleagues and the Personal View by Hargreaves and coauthors might be an introduction to the prevention cascade. This approach to understanding prevention adapts the cascade model now familiar in the assessment of treatment programmes. The prevention cascade starts with the recognition of risk—people and organisations developing prevention measures need to identify the population at risk for whom their prevention product, approach, or technology is designed, but the people in that population also need to acknowledge that risk. Some prevention measures such as HIV testing and counselling are applicable to the general population, whereas others are more targeted and specific to only a particular segment, such as voluntary medical male circumcision of men in areas with generalised epidemics. Garnett and colleagues illustrate how prevention cascades can be used, populating examples with data from Zimbabwe.
Smith and colleagues, in a modelling study, investigate the contributions of different prevention approaches including some of those on the wish-list—such as pre-exposure prophylaxis for women and a vaccine—to the trajectory of the epidemic in South Africa in the next 35 years. Smith and colleagues conclude that to maximise prevention benefits, programmes should focus on the scale-up of available interventions. Krishnaratne and co-workers summarise the weight of evidence for various interventions to strengthen the prevention cascade breaking them down into interventions to affect demand for, supply of, adherence to, and action of prevention approaches.
In the final paper in the issue, Dehne and colleagues set out a framework of how the ambitious UNAIDS targets to reduce the number of new infections to below 500 000 in 2020 might be achieved. The authors discuss the need for diverse actions at global, regional, national, and subnational levels and identify the groups responsible.
Cuba in 2015, and in the past few weeks Thailand, Armenia, and Belarus received validation from WHO that mother-to-child transmission of HIV has been eliminated. In Thailand, in 2015, just 85 children were born with HIV, down from 1000 a year at the turn of the millennium. This advance, in such diverse settings, gives hope that more countries will achieve this milestone and gives hope that the goal of an AIDS-free generation is achievable.
Key to successful prevention, highlighted by the papers in this issue, is the recognition of risk and the creation of demand among the at-risk populations. Some interventions, such as those to prevent mother-to-child transmission are an easy sell: with improvements in HIV treatment and accessibility to antiretroviral drugs very few women decline interventions that stop perinatal infection in their infants. Others, such as medical circumcision for men, on the face of it, present more of a challenge in generating demand, but successful programmes across sub-Saharan Africa have shown that willingness exists in priority populations when appropriate interventions to generate demand are provided. Where demand exists, programme developers must do their utmost to provide appropriate interventions, which drives home the absurdity of the National Health Service of England’s decision to deny pre-exposure prophylaxis to men who have sex with men.
As we continue to scale up treatment to achieve the 90-90-90 targets, other approaches to reducing new infections must not be forgotten. We can do much with existing interventions, but as the papers in this issue show evolution of programmes and technology will be needed to have the greatest effect.