From our current perspective, it is easy to forget that at the beginning of the AIDS pandemic, scientists did not even know the identity of the infectious agent causing a rare immunodeficiency. Rapid scientific advancement was needed to implement even basic public health measures such as laboratory-based testing to identify infected individuals and screen the blood supply.
In 1984, three years after the first AIDS reports, the human immunodeficiency virus was identified, followed the next year by the first licensed test. Following from these early advances, research has revealed the HIV disease process, developed major new therapies, and designed methods of prevention.
From treatment to combination prevention
Research has enabled scientists to discover two crucial things: key targets for antiretroviral therapies and then highly effective multi-drug regimens. Treatment has transformed the outlook for people living with HIV from almost certain death to a manageable chronic condition.
Critically, the treatment revolution led not only to vast improvement in human lives but also to crucial vehicles for prevention and public health. Beyond the success of preventing perinatal transmission, the two key public health breakthroughs are treatment as prevention, and pre-exposure prophylaxis.
The extraordinary success of research has brought a shift toward "combination prevention". This is defined as rights-based, evidence-informed, and community-owned programmes that use a mix of biomedical, behavioural, and structural interventions to have a sustained impact on reducing new infections.
Evidence-based prevention tools include pre-exposure prophylaxis, preventing perinatal transmission, universal treatment and voluntary male circumcision. These happen with testing, counselling, condoms, harm reduction, and education.
These developments have shifted the discourse over AIDS exceptionalism. The issue now is not so much that public health and civil liberties are in tension but rather that AIDS has captured a disproportionate amount of political attention and economic resources.
The very success of the AIDS movement has sparked a debate about the ethical allocation of scarce resources.
Game changing interventions
Although there is much to celebrate in the incredible scientific advances of the last three decades, key breakthroughs remain elusive. There is broad scientific consensus that "getting to zero" requires an effective vaccine.
Results from a 2009 trial in Thailand showed a 31% vaccine efficacy in preventing HIV infections. Although the vaccine conferred only modest protection, the results were the "proof of concept", instilling new hope for a game-changing intervention.
Recent work at Oregon Health and Science University reignited hope of an AIDS vaccine. In this study 16 rhesus monkeys infected with simian immunodeficiency virus were given an experimental vaccine. Nine were protected from the virus' effects and apparently "cleared" of infection.
The 2012 International AIDS Conference also saw renewed optimism toward a cure, with the report of the "Berlin patient". The patient was cured of the infection after a bone marrow transplant from a donor carrying the genetic variant, which provided resistance to HIV. There are two cases where people who underwent bone marrow transplants appeared to be virus-free once their antiretrovirals were stopped.
While bone marrow transplants will never be practical for large numbers of people, genetically based HIV treatment could emerge. In 2013, researchers announced that an HIV infected infant treated aggressively with antiretrovirals 30 hours after birth had no detectable viral levels at one month of age.
If confirmed, this case could transform treatment for newborns, providing hope for the estimated 330,000 HIV-infected infants in the developing world. Finding a cure would close a critical innovation gap, removing the need for arduous lifelong treatment regimes.
Another potentially game-changing innovation would be a female controlled prevention method, such as an effective vaginal microbicide gel. Clinical trials show it could be effective in reducing the risk of contracting HIV during sex. The option of taking preventive measures without their partner's agreement or knowledge would give women greater autonomy over their sexual health.
At the same time, scientists will be pressed to overcome the problems associated with current treatment regimes. These include drug resistance, chronic adverse effects and the need for more easily administered and cost-effective formulations. These breakthroughs require continued investment in research while addressing many pressing needs not only for HIV/AIDS, but in global health more broadly.
Allocating scarce resources
Even with considerable global funding devoted to HIV/AIDS (US$7.86 billion in foreign assistance in 2012), resources remain scarce. It requires agonising decisions on how to allocate life-saving interventions.
Who should receive treatment when all cannot access it? Should priority go to research, prevention, or treatment? And, ultimately, should AIDS receive a higher priority than other health threats? These are life-and-death questions for millions of people, and there is no consensus on the right answers.
Although resources have risen, drug scarcity is a fact of life, and will be for the foreseeable future. Without a major decrease in HIV incidence, competition for treatment resources will only become more intense.
While the global community cannot even meet current treatment needs, there will be additional calls for treatment expansion - for example, expanding PrEP. The future portends ever-increasing strains on existing drug resources in a time of scale austerity.
In a resource-constrained world, allocation decisions rest on multiple factors:
the level of immune dysfunction that triggers treatment initiation;
treatment costs (first- or second-line); and
the use of anti-retroviral therapy for prevention or treatment.
In allocating resources, which population groups, countries and regions deserve priority? Those with the greatest number of HIV-infected people, those with the lowest treatment coverage, or those where the most people can be reached at the lowest cost?
These are excruciating choices, as they often determine who will live when everyone cannot.
Lawrence O. Gostin does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.