100–100–100: a new, ambitious treatment target to end the HIV and hepatitis C epidemics
Authors: Joshua A Barocas
Journal: The Lancet Public Health (2022)

In 2014, UNAIDS put forth an ambitious target known as 90–90–90, the aims of which included that, by 2020, 90% of all people living with HIV should know their HIV status, 90% of all people with diagnosed HIV should be receiving sustained ART, and 90% of all people receiving ART should have viral suppression.1UNAIDS90–90–90: an ambitious treatment target to help end the AIDs epidemic.https://www.unaids.org/en/resources/documents/2017/90-90-90Date: Jan 1, 2017Date accessed: November 15, 2021Google Scholar In 2016, WHO proposed a global target for the elimination of hepatitis C virus (HCV) by 2030, which included the aims for 80% of eligible people with HCV to be treated, a 90% reduction in incident infections, and a 65% reduction in liver-related mortality.2WHOGlobal health sector strategy on viral hepatitis 2016–2021 towards ending viral hepatitis.https://apps.who.int/iris/handle/10665/246177Date: June 2016Date accessed: November 15, 2021Google Scholar Unfortunately, the global public health community failed to achieve the 90–90–90 HIV goals3UNAIDSGlobal HIV and AIDS statistics—fact sheet.https://www.unaids.org/en/resources/fact-sheetDate: 2021Date accessed: November 19, 2021Google Scholar and are unlikely to eliminate HCV by 2030.4Blach S Kondili LA Aghemo A et al.Impact of COVID-19 on global HCV elimination efforts.J Hepatol. 2021; 74: 31-36Summary Full Text Full Text PDF PubMed Scopus (99) Google Scholar Although more recent strategies, including the 2021 UNAIDS Global AIDS Strategy, proposing to end these epidemics acknowledge that structural factors restrict access to HIV and HCV services and the ability to achieve disease outcomes,5UNAIDSGlobal AIDS strategy 2021–2026: end inequalities, end AIDS.https://www.unaids.org/sites/default/files/media_asset/global-AIDS-strategy-2021-2026_en.pdfDate: 2021Date accessed: November 19, 2021Google Scholar they do not explicitly include those structural factors as part of the treatment paradigm. Although the global community's commitment to get people tested and treated for HIV and HCV is virtuous, it is often misaligned with individuals' basic survival needs, which are integral to treatment for any disease. In no population is this more apparent than in people who inject drugs (PWID). PWID are at a 29-times greater risk of acquiring HIV than people who do not inject drugs and account for up to 40% of new HCV infections annually worldwide.5UNAIDSGlobal AIDS strategy 2021–2026: end inequalities, end AIDS.https://www.unaids.org/sites/default/files/media_asset/global-AIDS-strategy-2021-2026_en.pdfDate: 2021Date accessed: November 19, 2021Google Scholar It should come as no surprise that the need to stave off withdrawal from opioids (which often involves reusing or sharing needles) or to find a safe place to sleep (which can be in exchange for drugs, injection equipment, or sex) often outcompete an individual's need to get an HIV test or take their medications. The continued push by global organisations such as UNAIDS and WHO for HIV and HCV treatment in this population without first addressing basic survival needs represents only a partial solution. Without evidence, however, of the extent to which these competing needs, such as housing instability, contribute to new infections, it might be difficult for public health practitioners and global organisations to reallocate time and resources away from downstream efforts, such as testing and antiviral treatment. In The Lancet Public Health, Jack Stone and colleagues6Stone J Artenie A Hickman M et al.The contribution of unstable housing to HIV and hepatitis C virus transmission among people who inject drugs globally, regionally, and at country level: a modelling study.Lancet Public Health. 2022; (published online Jan 7.)https://doi.org/10.1016/S2468-2667(21)00258-9Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar use two elegant yet simple dynamic, deterministic models to estimate the contribution of unstable housing to HIV and HCV transmission among PWID. Combining country-level data (including the estimated prevalence of HCV infection, HIV infection, homelessness, and injection drug use and the effect of treatment on opioid use disorder) from more than 50 countries and regions, with a valid model framework, they show that unstable housing will contribute 7·9% (95% credibility interval [CrI] 2·3–15·7) of new HIV infections and 11·2% (95% Crl 7·7–15·5) of new HIV infections among PWID in 2020–29. Although these models are partially limited by their assumptions and variable data quality from individual countries, the authors adequately quantify the uncertainty in their estimates such that they provide a reasonable snapshot of the scope of the problem. Stone and colleagues provide quantitative evidence that to consistently and substantially reduce HIV and HCV infections worldwide, competing physiological and safety needs among PWID must first be addressed. This means that structural barriers such as housing must first explicitly move into the purview of public health practice and research. Regarding HIV and HCV, as global organisations and public health practitioners consider how to get people tested and treated, they must concurrently consider how to secure stable housing, provide treatment for substance use disorders for those who want it, and maintain consistent and adequate access to harm-reduction services. The effect of such an approach could be profound. In the USA, for example, the authors estimated that 22·0% (95% CrI 6·9–37·2) of the HIV infections among PWID in 2020-29 will be attributable unstable housing.6Stone J Artenie A Hickman M et al.The contribution of unstable housing to HIV and hepatitis C virus transmission among people who inject drugs globally, regionally, and at country level: a modelling study.Lancet Public Health. 2022; (published online Jan 7.)https://doi.org/10.1016/S2468-2667(21)00258-9Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar By this author's rough calculations, this means that providing stable housing could prevent nearly 8000 of the 35 000 possible new HIV infections over this period. Global HIV and HCV elimination and treatment goals fail because the current treatment paradigm includes targeting the infections but excludes targeting the structural factors that allow the viruses to flourish. Global efforts will continue to fail until structural factors, such as housing, that influence the basic survival of people at risk, particularly PWID, are included as essential components of HIV and HCV prevention and treatment. To that end, we all—public health practitioners, clinicians, healthcare systems, global health organisations, and government leaders—must work towards 100–100–100, a new, ambitious, but achievable target that aligns more closely than current goals with individuals' need to survive. Alongside any HIV or HCV testing and treatment goals, the public health community should commit to supporting the aims of stably housing 100% of PWID who are unstably housed, providing 100% of PWID access to consistent and adequate harm reduction services, and offering treatment to 100% of PWID who want substance use treatment. Without achieving or, at least striving for, this 100–100–100 target, we are unlikely to eliminate HIV or HCV. I declare no competing interests The author would like to thank Julia Marcus for her thoughtful suggestions and edits to this piece. The contribution of unstable housing to HIV and hepatitis C virus transmission among people who inject drugs globally, regionally, and at country level: a modelling studyUnstable housing is an important modifiable risk factor for HIV and HCV transmission among people who inject drugs in many countries. The study emphasises the importance of implementing initiatives to mitigate these risks and reduce housing instability. Full-Text PDF Open Access