An Evaluation of Progress Towards the 2035 WHO End TB Targets in 40 High Burden Countries
Cha J., Thwaites G., Ashton P.
Abstract Tuberculosis (TB) is the leading global cause of death from a single infectious agent, with more than 10 million new cases annually. As a part of its efforts to control TB, the World Health Organisation (WHO) adopted the End TB Strategy in 2014 to reduce TB incidence by 90% between 2015 and 2035, with intermediate targets every five years. We examined TB incidence data from 2000 to 2018 for 40 high burden countries (HBCs) from the WHO published statistics, contextualized and assessed their trends over time, and projected the incidence to 2035 for each country. Two recurrent patterns accounted for 26 of the 40 HBCs: linear decrease (n = 14) or a peak in the 2000s followed by decline (n = 12). As uncontrolled HIV is the greatest risk factor for TB, trends in HIV infected and uninfected people were analysed separately for 15 Sub-Saharan African HBCs with high HIV prevalence. The projections of current trends were compared against the reductions required to meet the WHO End TB targets. Of the 25 countries without a high burden of HIV, only 5 are on track to meet the End TB targets: Ethiopia, Laos, Myanmar, Russia, and South Korea. Of the 15 high HIV burden countries, 6 are on track: Eswatini, Kenya, Lesotho, South Africa, Tanzania, and Zimbabwe. Three high HIV burden countries, Botswana, Namibia, and Zambia will miss the End TB targets due to the diminishing returns of indirectly decreasing TB incidence by controlling the HIV epidemic. Overall, we predict 62 million excess cases of TB between 2020 and 2035 in the 29 HBCs projected to miss the WHO End TB targets. In high HIV burden countries, new programs aimed directly at TB will be required to maintain momentum. Moreover, our projections are based on data prior to the COVID-19 pandemic; the disruption of the pandemic is overwhelmingly likely to interrupt vital TB services and increase TB incidence. We anticipate that these findings will help orientate countries to their progress towards the End TB goals and inform the level of investment required to meet these important targets for a TB-free world. Research in context Evidence before this study We searched PubMed and Google Scholar with the terms “End TB assessment,” “End TB Strategy,” or “WHO End TB” between June 2019 and September 2020 to identify studies in English reporting on progress towards meeting the End TB targets. We only identified two studies that carried out a quantitative assessment of current estimates against the End TB targets. One study limited its analyses to current estimates, rather than using statistical methods to produce projections based on current trends, while the other study and the WHO Global TB Report 2019 presented projections to 2020 only. No report provided a per-country estimate of the progress toward the End TB targets through 2035. Added value of this study This study presents projections of TB incidence from 2020 to 2035 for 40 high TB burden countries. We benchmark the progress of each country against the reductions necessary to meet the WHO End TB targets. We provide per country (rather than per WHO region) breakdowns of these numbers and place the results into broader global health and socio-political contexts. Additionally, we separately model incidence trends in HIV infected and uninfected populations to account for different trajectories in the two populations. Implications of all the available evidence Only 11 of the 40 countries assessed are on track to meet the 2035 End TB targets, leading to a total of 62 million excess cases of TB compared with if the targets were met. This is consistent with previous reports such as the WHO Global TB Report 2019, which found that only 11 of 30 high burden countries were on track to meet targets for 2020. We additionally demonstrate that TB specific programs should be developed in most high HIV burden countries, as reductions in TB in HIV uninfected people are declining much more slowly than in HIV infected people.