Producing HIV estimates: from global advocacy to country planning and impact measurement.

BACKGROUND: The development of global HIV estimates has been critical for understanding, advocating for and funding the HIV response. The process of generating HIV estimates has been cited as the gold standard for public health estimates. OBJECTIVE: This paper provides important lessons from an international scientific collaboration and provides a useful model for those producing public health estimates in other fields. DESIGN: Through the compilation and review of published journal articles, United Nations reports, other documents and personal experience we compiled historical information about the estimates and identified potential lessons for other public health estimation efforts. RESULTS: Through the development of core partnerships with country teams, implementers, demographers, mathematicians, epidemiologists and international organizations, UNAIDS has led a process to develop the capacity of country teams to produce internationally comparable HIV estimates. The guidance provided by these experts has led to refinements in the estimated numbers of people living with HIV, new HIV infections and AIDS-related deaths over the past 20 years. A number of important updates to the methods since 1997 resulted in fluctuations in the estimated levels, trends and impact of HIV. The largest correction occurred between the 2005 and 2007 rounds with the additions of household survey data into the models. In 2001 the UNAIDS models at that time estimated there were 40 million people living with HIV. In 2016, improved models estimate there were 30 million (27.6-32.7 million) people living with HIV in 2001. CONCLUSIONS: Country ownership of the estimation tools has allowed for additional uses of the results than had the results been produced by researchers or a team in Geneva. Guidance from a reference group and input from country teams have led to critical improvements in the models over time. Those changes have improved countries' and stakeholders' understanding of the HIV epidemic.

What will it take to achieve virtual elimination of mother-to-child transmission of HIV? An assessment of current progress and future needs.

BACKGROUND: The number of HIV-positive pregnant women receiving antiretroviral drugs (ARVs) to prevent mother-to-child transmission (MTCT) of HIV has increased rapidly. OBJECTIVE: To estimate the reduction in new child HIV infections resulting from prevention of MTCT (PMTCT) over the past decade. To project the potential impact of implementing the new WHO PMTCT guidelines between 2010 and 2015 and consider the efforts required to virtually eliminate MTCT, defined as <5% transmission of HIV from mother to child, or 90% reduction of infections among young children by 2015. METHODS: Data from 25 countries with the largest numbers of HIV-positive pregnant women were used to create five scenarios to evaluate different PMTCT interventions. A demographic model, Spectrum, was used to estimate new child HIV infections as a measure of the impact of interventions. RESULTS: Between 2000 and 2009 there was a 24% reduction in the estimated annual number of new child infections in the 25 countries, of which about one-third occurred in 2009 alone. If these countries implement the new WHO PMTCT recommendations between 2010 and 2015, and provide more effective ARV prophylaxis or treatment to 90% of HIV-positive pregnant women, 1 million new child infections could be averted by 2015. Reducing HIV incidence in reproductive age women, eliminating the current unmet need for family planning and limiting the duration of breastfeeding to 12 months (with ARV prophylaxis) could avert an additional 264 000 infections, resulting in a total reduction of 79% of annual new child infections between 2009 and 2015, approaching but still missing the goal of virtual elimination of MTCT. DISCUSSION: To achieve virtual elimination of new child infections PMTCT programmes must achieve high coverage of more effective ARV interventions and safer infant feeding practices. In addition, a comprehensive approach including meeting unmet family planning needs and reducing new HIV infections among reproductive age women will be required.

Antiretroviral therapy needs: the effect of changing global guidelines.

BACKGROUND: In 2010 the WHO issued a revision of the guidelines on antiretroviral therapy (ART) for HIV infection in adults and adolescents. The recommendations included earlier diagnosis and treatment of HIV in the interest of a longer and healthier life. The current analysis explores the impact on the estimates of treatment needs of the new criteria for initiating ART compared with the previous guidelines. METHODS: The analyses are based on the national models of HIV estimates for the years 1990-2009. These models produce time series estimates of ART treatment need and HIV-related mortality. The ART need estimates based on ART eligibility criteria promoted by the 2010 WHO guidelines were compared with the need estimates based on the 2006 WHO guidelines. RESULTS: With the 2010 eligibility criteria, the proportion of people living with HIV currently in need of ART is estimated to increase from 34% to 49%. Globally, the need increases from 11.4 million (10.2-12.5 million) to 16.2 million (14.8-17.1 million). Regional differences include 7.4 million (6.4-8.4 million) to 10.6 million (9.7-11.5 million) in sub-Saharan Africa, 1.6 million (1.3-1.7 million) to 2.4 million (2.1-2.5 million) in Asia and 710 000 (610 000-780 000) to 950 000 (810 000-1.0 million) in Latin America and the Caribbean. CONCLUSIONS: When adopting the new recommendations, countries have to adapt their planning process in order to accelerate access to life saving drugs to those in need. These recommendations have a significant impact on resource needs. In addition to improving and prolonging the lives of the infected individuals, it will have the expected benefit of reducing HIV transmission and the future HIV/AIDS burden.

The global impact of scaling up HIV/AIDS prevention programs in low- and middle-income countries.

A strong, global commitment to expanded prevention programs targeted at sexual transmission and transmission among injecting drug users, started now, could avert 28 million new HIV infections between 2005 and 2015. This figure is more than half of the new infections that might otherwise occur during that period in 125 low- and middle-income countries. Although preventing these new infections would require investing about U.S.$122 billion over this period, it would reduce future needs for treatment and care. Our analysis suggests that it will cost about U.S.$3900 to prevent each new infection, but that this will produce a savings of U.S.$4700 in forgone treatment and care costs. Thus, greater spending on prevention now would not only prevent more than half the new infections that would occur from 2005 to 2015 but would actually produce a net financial saving as future costs for treatment and care are averted.