On the 30th anniversary of the first description of AIDS, there is much progress to celebrate, but still much work to be done. Research breakthroughs continue to improve treatments and to provide evidence for newer, better strategies that could help people to protect themselves from infection and prevent those infected from spreading the virus. Just last month, researchers reported a study, sponsored by the US National Institutes of Health, showing that when patients are treated early it reduces the chance that they will pass the virus on to uninfected partners by 96% (see http://go.nature.com/e5e9m7). That study is the latest, and perhaps strongest, evidence to support the concept of 'treatment as prevention' — the use of antiretroviral drugs in people who are newly infected, or even in uninfected people in high-risk groups, to slow the spread of AIDS.

In one of two Comments published in this issue (see page 29), Salim Abdool Karim at the University of KwaZulu-Natal in Durban, South Africa, details other recent successes in treatment as prevention, including a trial he conducted with colleagues in which women who used a vaginal gel containing an antiretroviral drug were less likely to become infected with HIV. Another study released last year showed that prophylactic antiretrovirals can cut the risk of new infections among men who have sex with men (R. M. Grant et al. N. Engl. J. Med. 363, 2587–2599; 2010). As he points out: “stopping the epidemic is within our grasp”.

If we do not move forwards, 30 years from now the toll of the disease will have multiplied.

But it is not a given that new biomedical interventions alone can slow the spread of AIDS. Six million people with HIV in developing countries now receive antiretroviral treatment, a remarkable accomplishment, but the Joint United Nations Programme on HIV/AIDS (UNAIDS) estimates that about 10 million people who need treatment aren't getting it. If the world cannot afford to treat the people who already need it, who will finance the expansion of treatment to people in the early stages of infection — as the World Health Organization recommends — or to high-risk groups who are not even infected? Advocates of universal access to antiretroviral drugs argue that providing early treatment to everyone who needs it is imperative, but how do we define 'need' when discussing preventative measures?

Money matters

These questions take on more weight in a time of global financial trouble, when big donors such as the United States are consumed with budget cutting, and Europe's finances are being drained by bail-outs of banks and countries in financial difficulty.

In an encouraging move, US Ambassador Eric Goosby has started a discussion within the US government on what it might take for the world to treat everyone now infected with HIV, which, the study released last month suggests, would drastically slow the spread of the virus. Goosby heads the President's Emergency Plan for AIDS Relief, which already spends nearly US$7 billion a year, and aims to treat 4 million people across 88 countries. This conversation is a helpful part of the ongoing worldwide effort by the Global Fund to Fight AIDS, Tuberculosis and Malaria, and others to coax donor countries to underwrite the roll-out of a global strategy, based on expanded access to antiretrovirals, to drastically curtail the spread of AIDS.

Implementing such a strategy would also require overcoming a hurdle that dogs AIDS-prevention efforts. Abdool Karim writes that a staggering proportion of people do not know they are infected with HIV because of the fear and stigma that prevents them from getting tested. This situation is acute in Abdool Karim's home of South Africa, where former president Thabo Mbeki denied for years that HIV causes AIDS. But it is a problem around the world: the UNAIDS estimates that only about half of the 33 million people living with HIV know their HIV status, and this is an obvious impediment to getting treatment to everyone who needs it.

Cost–benefit analysis

If the cost of providing treatment for prevention seems enormous, the cost of inaction is far greater, writes Lucie Cluver at the University of Oxford, UK, in a second Comment, on page 27 of this issue.

Cluver led the developing world's first longitudinal study of the impact on children of parents made ill or killed by AIDS. The study, begun in 2005, has revealed the heartbreaking toll of the disease. Those orphaned by AIDS are more likely than children orphaned by other causes, including homicide and suicide, to develop post-traumatic stress disorder. Children of parents who are sick with AIDS are more likely to be depressed or to have an anxiety disorder than those whose parents are sick owing to other causes. Children in families affected by AIDS do worse at school and are more likely to engage in prostitution, which, in turn, makes them more vulnerable to becoming infected with HIV themselves. The toll of AIDS on the economies of developing nations can undermine these countries' attempts to escape poverty.

Poor countries now bear the brunt of AIDS, in contrast to 30 years ago, when AIDS was mainly a disease of white homosexual men in rich countries. Antiretroviral drugs are credited with curtailing the disease in these communities, but the truth is that slowing the spread required social norms to change as well.

Next week, governments will meet in New York at a United Nations meeting to plan the global response to AIDS for the next decade. They should endorse calls by UN secretary-general Ban Ki-Moon for funds to get 13 million people on antiretrovirals by 2015. The world has an ever-expanding biomedical toolbox for HIV, but to curb the disease's spread, this must be coupled with efforts to change social and cultural norms. If we do not move forwards along this path, 30 years from now the toll of the disease in terms of lives lost and human potential wasted will have multiplied. And history will harshly judge the world's inability to capitalize on its chance to avert a worsening of this disaster.