2010 is an important year for the HIV response in Asia and the global HIV movement. It is the year by which the United Nations General Assembly pledged to ensure universal access to HIV treatment for those in need . It also marks a major milestone for efforts aimed at achieving the Millennium Development Goal (MDG) 6 to ‘halt and reverse the spread of HIV by 2015’ . Only a few countries in Asia are on track to meet this target by 2015  due to a widespread failure or reluctance to properly address the local epidemiological contexts and to target the most-at-risk populations among whom the epidemic is largely concentrated such as people who use drugs (and their partners), men who have sex with men (MSM), and sex workers (and their clients).
Asia is a very populous region with concentrated HIV epidemics. This article analyzes the evolution of the epidemic across the region, examines the context within which the epidemic is evolving, and outlines the key actions to address the persistent challenges faced by countries and most-at-risk populations. It provides a short overview of the epidemic and then, drawing heavily upon new evidence presented elsewhere in this issue of AIDS, it discusses key actions that can help address the problems faced across the region.
The evolving context: HIV in Asia
Asia is a heterogeneous region in terms of culture, wealth, geography, and demographics – as well as in HIV transmission patterns and prevalence. The region is home to the largest number of people living with HIV outside sub-Saharan Africa (Fig. 1). According to Joint United Nations Programme on HIV/AIDS (UNAIDS) estimates, between 3.8 and 5.5 million people were living with HIV in Asia in 2008 (compared to between 20.8 and 24.1 million in sub-Saharan Africa, between 1.8 and 2.2 million in Latin America, and between 710 000 and 970 000 in Western Europe), for example. The figure for Asia includes an estimated 350 000 new infections in 2008 alone . However, in contrast to the generalized epidemic in sub-Saharan Africa, it is broadly acknowledged that the epidemic across Asia is ‘concentrated’ – defined by UNAIDS and WHO as a situation in which ‘HIV prevalence is consistently over 5% in at least one defined subpopulation, but is below 1% in pregnant women in urban areas (UNAIDS and WHO are not prescriptive about which ‘subpopulation’) .
Since its peak in the mid-1990s, estimated HIV incidence in the general population had declined by more than half across Asia by 2000 and has remained relatively stable since then. However, the prevalence remains high in most-at-risk populations such as people who inject drugs, of which an estimated 16% are living with HIV across Asia .
Achievements across Asia
Data from UNAIDS show that the annual number of new HIV infections in Asia declined by 12.5% between 2001 and 2008, and the number of children newly infected with HIV declined by a third . Asia has demonstrated notable successes with national prevention programs. For example, Cambodia and Thailand, countries with the highest HIV prevalence in the region, have succeeded in reducing the number of people living with HIV by 37.5 and 19.7%, respectively, between 1997 and 2007 . Thailand has employed, to varying degrees, condom distribution, sexually transmitted infection testing, harm reduction programs, mass media campaigns, national surveillance systems, civil society engagement, and targeted prevention efforts to change the trajectory of the epidemic . Most importantly, access to antiretroviral therapy has been scaled up greatly across the region , with 570 000 people receiving the life-saving intervention in 2009: two-thirds through Global Fund-supported programs, and the majority in some countries through national health budgets (e.g., Thailand) . However, coverage still needs to improve further.
Key challenges that remain to be addressed
While differences in the epidemiology of, and the responses to, HIV epidemics exist between and within countries in Asia, several important issues that broadly affect the region demand urgent attention. These relate to the needs of most-at-risk populations, legal and policy obstacles to accessing services, factors that hinder the development of high-impact programs targeting those in need, the provision of continuous funding for a sustainable response, prevention and treatment scale-up, and strategies to develop a systematic approach for addressing the epidemic.
The HIV epidemic in Asia is largely concentrated among people who inject drugs, sex workers, and men who have sex with men (MSM). Yet these groups often face stigma, discrimination, criminalization, and marginalization in their daily lives – experiencing, as a result, significant barriers to the utilization and accessibility of potentially life-saving HIV prevention and treatment services. Fully analyzing and understanding the local situation in terms of HIV epidemiology and the barriers to services is critical if scarce resources are to be allocated in the most effective and efficient way to limit HIV transmission.
Analysis has been conducted to map patterns of sex work against the HIV epidemic in the region to demonstrate linkages in countries such as Indonesia and Malaysia, and some regions of India and China [9,10]. It demonstrates the heterogeneous patterns of sex work that exist across the region and that require tailored HIV prevention programs that are relevant to specific contexts. Countries must prioritize well organized and operationalized prevention programs targeting sex workers and their clients, providing adequate resources and safe and legal working environments.
Targeting prevention among people who inject drugs will have a high impact in many Asian countries. In Bangladesh, for example, around 90% of HIV infections are associated with injecting drug use, with high rates also reported in China (38.5%) and Indonesia (46%) . A substantial overlap between injecting drug use and sex work exists across the region. In the Sichuan province of China, for example, UNAIDS reports that over 40% of women who inject drugs and 34% of men who inject drugs were also involved in sex work . This overlap can also be found across Eastern Europe, particularly the countries of the former Soviet Union, which share many similarities with Asia in terms of at-risk populations and the HIV epidemic . In countries where HIV prevalence among sex workers has not yet reached substantial levels, epidemics can be avoided or delayed by also expanding prevention activities for people who inject drugs, as the virus is likely to spread between these groups, according to Bergenstrom and Abdul-Quader .
However, national HIV prevention, treatment, and care efforts for people who inject drugs are limited. Harm reduction programs have lagged behind the growth of the epidemic and in many settings have been initiated too late (or too weakly) to have the desired impact. For example, there are still 15 countries in Asia where opioid substitution therapy is not available [11,12]. In many other countries, such as China, India, and Thailand, these interventions do exist but with low coverage (reaching less than 5% of people who inject drugs) . Although the number of needle and syringe programs in Asia has increased over recent years, government-funded programs exist in only four of the 11 countries with reported epidemics among people who inject drugs . The introduction of, and increased access to, such programs as well as antiretroviral therapy for people who use drugs must be a top health priority across Asia.
Men who have sex with men face similar problems to those described above in terms of accessing essential HIV services in Asia, and they are also often subjected to stigma and discrimination. A review by van Griensven and van Wijngaarden  found severe HIV epidemics among MSM across Asia. They reported double-digit HIV prevalence among men who have sex in cities in China, Taiwan, India, Myanmar, and Thailand. As Bridge et al.  highlight, these individuals also often report numerous sexual partners and may have heterosexual intercourse – further increasing the risk of transmission. According to Rao et al. , sex between men is criminalized in 15 countries in Asia − a substantial barrier to effective HIV prevention.
Analysis by Greener and Sarkar  identifies socioeconomic patterns of HIV transmission in Asia and explores how factors such as social deprivation and poverty contribute to the adoption of high-risk behaviors. They find no relationship between gross national income per capita and HIV prevalence at the country level. However, in countries such as Cambodia and India, higher HIV prevalence is shown in poorer households. A positive correlation is demonstrated between the proportion of men visiting sex workers and HIV prevalence , which further underscores the significance of sex work in the evolution and control of HIV epidemics in Asia . However, their findings indicate a multidimensional link between underlying social and cultural factors and the risks of HIV infection, with no indication of a single underlying explanation for risk behaviors that fuel the HIV epidemic in Asia.
Csete and Grover  review the adverse impacts of applying criminal law to most-at-risk populations and emphasize the importance of investing resources in reforming legislation related to sex work, drug use, homosexuality, and the transmission of HIV. According to Rao et al. , ‘the criminalization of these risk behaviors can effectively neutralize otherwise supportive HIV policies'. Many of the articles in this issue of AIDS underline the importance of harmonizing national laws and HIV policies and enabling policy dialogue between authorities to address legal issues. For example, in 2003, Thailand's zero-tolerance approach toward people who use drugs resulted in the deaths of more than 2000 people and the arrest of several thousand more, according to the Human Rights Watch . Due in part to international pressure and funding, the legal and policy framework in Thailand is changing to embrace human rights and harm reduction strategies.
Understanding the epidemics
It is also clearly important to improve the quality and availability of epidemiological data to guide HIV programming across Asia. Bangladesh and the Philippines are two examples of countries with low service coverage among most-at-risk groups as illustrated by Rao et al. . The same study found that eight countries in Asia did not provide any data on high-risk groups when reporting progress on UNGASS indicators to the United Nations in 2007, demonstrating a gap in knowledge about the dynamics of HIV epidemics in Asia.
High-impact programs targeting those in need
Komatsu et al.  highlight a continuing gap in funding for interventions that target high-risk groups, demonstrating a disproportionately low spending from the Commission on AIDS in Asia for prevention targeting these groups: US$ 81 million compared to US$ 247 million spent on prevention efforts for the general population in 2007. Bergenstrom and Abdul-Quader  stress the need for further research to estimate the resource needs and gaps regarding programs targeting people who inject drugs.
Even though resources aimed at high-risk groups remain disproportionately low, overall funding for HIV programs has increased in the past decade, in part due to the Global Fund to Fight AIDS, Tuberculosis and Malaria, the World Bank, and the US President's Emergency Plan for AIDS Relief. By May 2010, the Global Fund alone had approved an investment of over US$ 2 billion for HIV programs in its south and west Asia, and east Asia and the Pacific subregions . In 2009, the Global Fund financed two-thirds of the antiretroviral treatment provided in the Asian region . It has also become the largest supporter of harm reduction for people who inject drugs – investing an estimated US$180 million – and of prevention efforts aimed at sex workers in the region (except for India) . The Global Fund has also supported numerous programs that focus on men who have sex with men.
Collectively, international donors have an ongoing commitment to all people living with HIV in Asia and must ensure long-term, reliable, and responsible funding for HIV prevention, treatment, and care. According to Komatsu et al. , Asian countries with growing economies, such as China and India, should prioritize HIV within their domestic budgets and mobilize increased resources while recognizing the contribution of high-risk groups to HIV transmission. Thailand is a good example of an Asian country which has managed to transition the cost burden of antiretroviral therapy from international donors and programs into domestic budgets, thus internalizing the costs and providing more secure and consistent funding.
Achieving scale-up of HIV services, including prevention, testing, and treatment is a critical next step. Srikantiah et al.  highlight that the coverage of HIV services is extremely low in the nine Asian countries that account for 95% of the HIV burden in low-income and middle-income countries in the region. In these countries, only around 500 000 people living with HIV (less than 10% of the total number of people on treatment in the region) were receiving antiretroviral therapy through nationally funded programs in 2008. Treatment is life-long, so strategies to expand initial access but also to retain patients on treatment are crucial. High-impact interventions should also be incorporated into existing programs and services as part of a more comprehensive strategy .
Many Asian governments are expanding the availability of testing but, as Sullivan et al.  highlight, there are still significant challenges and barriers to overcome. Their article emphasizes the usefulness of strategies such as provider-initiated testing and counseling that do not passively rely on people seeking services, but take an active approach. Across Asia, some countries are more effective than others in promoting testing. In Thailand, a country with one of the largest HIV-positive populations in the region, an estimated 57% of the total HIV cases in the country have been diagnosed and notified. In Vietnam, around 54% have been notified. However, only an estimated 3% of HIV infections in Pakistan have been formally diagnosed and notified to the relevant health information systems .
Addressing barriers to testing requires attention to the complex social, interpersonal, emotional, and financial difficulties that follow a positive HIV test. Political commitment and openness in this matter is critical in terms of reducing stigma and discrimination and removing the legal and contextual barriers that hinder the uptake of efficient prevention, treatment, and care. Srikantiah et al.  demonstrate that the participation of people living with HIV in service delivery and program design can enhance linkages between communities and facility-based services. Establishment of such linkages has been instrumental in reducing HIV-related stigma in Cambodia and Thailand.
The need for a systematic approach to overcome challenges
HIV surveillance in Asia has improved over the past decade, notably in Cambodia and China . However, large gaps in monitoring and information systems continue to impede focused HIV responses. A comprehensive approach to strategic information collection and to developing the capacity to use the data is presented by Azim et al. . This study builds upon experiences from countries that have succeeded in using data when planning their HIV response and stresses the importance of understanding the specific contexts and details of HIV epidemics to generate an adequate response. Strategic data collection to guide, monitor, and evaluate progress is particularly important across Asia, where heterogeneous epidemics remain largely concentrated and unresolved.
Both Rao et al.  and Srikantiah et al.  emphasize the importance of systematic approaches to tackling HIV in Asia. Low-Beer and Sarkar  identify components required for a systematic public health approach for scaling up HIV prevention in Asia, drawing on success stories in Asia which show reversals in the spread of HIV where prevention efforts have been systematically scaled up (such as in Cambodia, Thailand, and southern India). Coverage expansion of individual interventions, particularly those aimed at high-risk groups, was effective when accompanied by efforts targeting social change at the population level. Other examples included the disaggregation of epidemiological data and the systematic and intensive engagement of high-risk groups.
Consequences of not acting
According to UNAIDS, there were 350 000 new HIV infections in Asia in 2008 (down slightly from the corresponding estimate in 2001). This includes 21 000 new HIV infections among Asian children in 2008 . If national HIV responses are not significantly strengthened in the region, it is estimated that the economic consequences of HIV and AIDS by 2015 will force an additional 6 million Asian households into poverty . Crucially, the development of HIV in the region from a concentrated epidemic to a more generalized one could have disastrous consequences for the global HIV response: the generalized HIV epidemic across the less-populated Sub-Saharan Africa region resulted in 1.9 million new infections in 2008 . Even if the HIV epidemics were to grow in only China and India alone – collectively home to around 2.5 billion people – the consequences would be severe.
In a time of economic crisis, it is of paramount importance that sufficient resources are raised and committed by multilateral and bilateral donors, the private sector, and national budgets. A reduction or stagnation in the international response to HIV in Asia could jeopardize the achievements made or even reverse recent progress . Resources must then be spent effectively to ensure the highest possible impact. Most importantly, an effective response will require the region's leaders to take ultimate responsibility in controlling HIV in Asia.
Although there have been many successes in the past decade in terms of responding to the HIV epidemics in Asia, substantial challenges remain in expanding and extending the response to high-risk groups in Asia. These must be overcome in order to reach the MDGs and achieve universal access to HIV treatment. Evidence from the studies analyzed reinforces the need to target most-at-risk populations and high-risk behaviors, to address the legal and social barriers faced by marginalized and stigmatized high-risk groups, to adopt systematic approaches, and to learn from other countries (and from other regions) in moving forward.
The potential consequences of inaction in Asia are huge – an increase in HIV prevalence in this densely populated region could have disastrous implications for the global HIV response. There is a need across Asia for increased funding from all sources – but also for engaged leadership and political commitment to ensure that resources are spent effectively to ensure the highest possible impact. In Asia, inaction is not an option.
The views expressed in this paper are those of the authors and do not necessarily represent the position of the Global Fund to Fight AIDS, Tuberculosis and Malaria.
Conflicts of Interest: None.