MarkusHaackerThe Economics of the Global Response to HIV/AIDSOxford University Press, 2016. 304 p. $55.00.

Over the past quarter century the HIV virus has spread to all corners of the globe, resulting in one of the deadliest pandemics of modern times. Since the beginning of the pandemic, more than 70 million people have been infected with HIV and about half of them have died of AIDS. The pandemic has evolved rapidly and can be roughly divided into three phases. The first is the period of expansion from the mid-1980s through the late 1990s when the virus spread widely. The response then largely consisted of preventive measures such condom distribution. Next, in the early 2000s, as the cost of antiretroviral treatment (ART) dropped sharply, a massive global effort was initiated to make ART available in all countries. As a result, 17 million people worldwide are now on ART, about half of those who need it. In the latest phase, AIDS has evolved into a chronic disease in most countries, and several of the key epidemiological indicators have leveled off or declined. HIV/AIDS policy has moved from an emergency mode to an emphasis on sustainability and cost-effectiveness. In monitoring the pandemic, it is crucial to distinguish between cumulative and annual numbers. Cumulative estimates such as global numbers of deaths and infections continue to rise because new infections and AIDS deaths keep occurring. In contrast, the annual number of events have started to decline. For example, the number of AIDS deaths dropped from 2.0 million in 2005 to 1.1 million in 2015, accounting for 2 percent of all deaths in the latter year. HIV/AIDS is no longer in the top ten causes of global deaths. Annual new infections are also down from 3.5 million at the peak in 1997 to 2.1 million in 2015. This is good news, but the pandemic is far from over. The number of new infections has ceased to decline in the past three years and has leveled off at 2.1 million per year. This is nearly double the number of new AIDS-related deaths. As a result, the number of people living with HIV, now at 36.7 million, continues to rise. This volume takes an expert look at various economic dimensions of the epidemic. In successive sections the author examines the global health and economic impact, the global response, and the design and financing of HIV/AIDS policies. The most important impact of the epidemic is on health and mortality. In the hardest-hit countries in Southern Africa, with about one in five adults aged 15–49 infected, the death rate nearly doubled and life expectancy declined by two decades between the late 1980s and the peak of the pandemic. This unprecedented health shock is felt particularly at the individual and household level. In other sub-Saharan regions the pandemic has been less severe and, for sub-Saharan Africa as a whole, the average HIV prevalence at its peak was only 5 percent, with a proportionally lower impact on mortality. In most of the developed world ART is now widely available and the AIDS death rate is low. For example, in the US the annual number of deaths from AIDS has dropped to 0.5 percent of all deaths. The adverse health impact and the humanitarian motive provided strong rationales for the international effort to halt the pandemic, but there were other motives as well. First, in the initial stages of the pandemic, there was fear within the developed world that HIV was a highly communicable virus threatening to leap to its shores. Global public-good logic demanded a stiff global response. That response has not occurred, but political interests were served. A second and still important reason for intervention was the poverty impact in the poorest afflicted countries. Past studies have demonstrated a strong association between rising life expectancy and economic performance that in part operates through the higher productivity of a healthier labor force. However, after an examination of the relevant evidence, the author concludes that the expected economic decline has not occurred (“the evidence for any impact of HIV/AIDS on GDP per capita is very weak”). As explicated in the book, the reason for this finding are not altogether clear. The global response to the epidemic has been unprecedented. The Joint United Nations Programme on HIV/AIDS (UNAIDS) was launched in 1995 to coordinate the HIV/AIDS–related activities of its co-sponsoring UN agencies. Its mandate was to organize the expanded global response to HIV/ AIDS and to achieve universal access to HIV prevention, treatment, care, and support. The main impact of these efforts had to wait until the early 2000s when ART treatment became sufficiently affordable to allow its introduction into the poorest countries. The number of patients on ART in Africa was small in the early 2000s but reached 12.1 million in 2015. Gains were greatest in the continent's most-affected regions, Eastern and Southern Africa, where coverage of those in need increased from 24 percent in 2010 to 54 percent in 2015. The expansion of treatment to low-income countries became possible as a result of large-scale funding from the US President's Emergency Plan for AIDS Relief (PEPFAR), initiated by President George W. Bush, and the Global Fund to Fight AIDS, Tuberculosis and Malaria. External resources to fund the global HIV/AIDS control effort rose sharply over time from $0.5 billion in the mid-1990s to $15.6 billion in 2016. But this flow of funding has stabilized in recent years. Prospects for further increases are not promising, as governments in the developed world are turning increasingly to domestic concerns. A second stream of funding for the epidemic consists of domestic resources, which have also risen over time and now constitute 57 percent of the total resources for HIV in low- and middle-income countries. Further increases in domestic resources will be needed to raise the coverage of ART, which still covers only half of those in need. The effects of this massive international intervention are evident in mortality statistics. The earlier large declines in life expectancy were reversed and individuals on ART can expect to live a near-normal life if treatment starts early and is continuous. While ART certainly deserves much credit for the decline in AIDS deaths, there is another and often neglected factor. Specifically, the number of new infections rose until the mid-1990s, peaked in 1997, and then declined. Since it takes on average about a decade between infection with HIV and an untreated AIDS death, one would expect to have seen a decline in AIDS deaths even in the absence of ART. Of course, the wide availability of ART accelerated the rate of decline in deaths. The reason for the peaking and subsequent drop in the annual number of new infections after 1997 remains a puzzle. The possible explanations offered here include the rapid early infection of the highest-risk populations, so that the remaining uninfected population became progressively lower-risk over time. In addition, it is likely that behavior change (e.g., condom use and reduction in the number of casual partners) played a role as the epidemic became better known (e.g., through an increase in AIDS funerals) and government efforts to promote HIV prevention became more prominent. Whatever the cause, the decline in the incidence of HIV was a key turning point in the epidemic. The international response to the pandemic has been the subject of extensive debate. The critics’ arguments are summarized in a provocative section entitled “Has the global HIV/AIDS response received too much money?” There are two main reasons for suggesting that overall health outcomes could be improved by diverting some fraction of HIV/AIDS funds to other health services: 1) the proportion of health funding allocated to HIV/AIDS is much higher than the pandemic's proportion of the global burden of disease, and 2) the cost-effectiveness of ART is considerably lower than for a number of other health interventions. The author does not dispute these points but simply asserts that the response to HIV/AIDS has been “effective but also expensive.” The book's third part deals with the design and financing of HIV/AIDS policies. It is more technical and primarily aimed at an audience of economists. The objective is to use cost-effectiveness analysis to design optimal HIV/AIDS strategies—a complex task that often involves computer models. A first difficulty is to decide what is to be optimized: HIV infections or AIDS deaths averted, life years lived, life expectancy, or economic indicators? Then there are a range of interventions available including prevention (condoms, male circumcision, treatment-as-prevention, mother-to-child transmission) and ART treatment. Another choice is whether to focus on core groups of high-risk individuals or on the general population. Moreover, epidemics differ among populations and one prescription does not fit all. Despite these complexities, the author reaches an important general conclusion: cost-effectiveness analysis models should have long time horizons. The importance of this is clear when one compares an investment in treatment of an AIDS patient, which gives an instantaneous result, with an investment in the prevention of an infection, which has very limited impact for years but then saves treatment costs for many years. With a short time horizon, prevention could receive too little attention. The complexity of the discussion of optimal strategies has led the international community to rally around a simple and clear goal referred to as the 90-90-90 initiative to end the pandemic. The objective for 2020 is that 90 percent of all people living with HIV will know their HIV status, 90 percent of all people with diagnosed HIV infection will receive sustained antiretroviral therapy, and 90 percent of all people receiving antiretroviral therapy will have experienced viral suppression. This effort puts treatment-as-prevention at its center. The author appears to be skeptical that this can be achieved. One of the most significant obstacles is to identify HIV-infected individuals (most of whom are asymptomatic) and persuade them to take ART for the rest of their lives. This will be very expensive. Other prevention approaches (condoms and male circumcision) are much more cost-effective than treatment-as-prevention. The large amounts of additional funding required for full implementation of 90-90-90 are also unlikely to be made available, since both international donor and within-country resources for HIV/AIDS are facing increasing competition from other pressing needs. This book's focus on economics makes it uniquely valuable and interesting for the mostly non-economist readers of this journal. Policymakers, program managers, and researchers will gain much new insight from the rich and thoughtful discussion. If there is a flaw, it is that the author—like US President Harry Truman's proverbial two-handed economist—is sometimes too evenhanded. He is so familiar with the literature that he can cite studies on both sides of any issue. This provides valuable information but sometimes leaves key issues unresolved. For example, by raising the question of whether we are spending too much on HIV/AIDS versus other health interventions, one can infer that this is at least a reasonable question to ask even though no clear answer is provided. On the issue of treatment-as-prevention, he states several times that it is expensive but offers no explicit critique of the 90-90-90 goals. This leaves this reader with the suspicion that we may not be on an optimal policy trajectory, despite the remarkable success of the global HIV/AIDS response in reversing epidemic mortality. In the meantime 2.1 million new infections continue to occur each year.

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