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. 2023 Apr;11(4):e546-e555.
doi: 10.1016/S2214-109X(23)00045-1.

The impact of alternative delivery strategies for novel tuberculosis vaccines in low-income and middle-income countries: a modelling study

Rebecca A Clark  1 , Christinah Mukandavire  2 , Allison Portnoy  3 , Chathika K Weerasuriya  2 , Arminder Deol  2 , Danny Scarponi  2 , Andrew Iskauskas  4 , Roel Bakker  5 , Matthew Quaife  2 , Shelly Malhotra  6 , Nebiat Gebreselassie  7 , Matteo Zignol  7 , Raymond C W Hutubessy  8 , Birgitte Giersing  9 , Mark Jit  10 , Rebecca C Harris  11 , Nicolas A Menzies  12 , Richard G White  2
Affiliations

The impact of alternative delivery strategies for novel tuberculosis vaccines in low-income and middle-income countries: a modelling study

Rebecca A Clark et al. Lancet Glob Health. 2023 Apr.

Abstract

Background: Tuberculosis is a leading infectious cause of death worldwide. Novel vaccines will be required to reach global targets and reverse setbacks resulting from the COVID-19 pandemic. We estimated the impact of novel tuberculosis vaccines in low-income and middle-income countries (LMICs) in several delivery scenarios.

Methods: We calibrated a tuberculosis model to 105 LMICs (accounting for 93% of global incidence). Vaccine scenarios were implemented as the base-case (routine vaccination of those aged 9 years and one-off vaccination for those aged 10 years and older, with country-specific introduction between 2028 and 2047, and 5-year scale-up to target coverage); accelerated scale-up similar to the base-case, but with all countries introducing vaccines in 2025, with instant scale-up; and routine-only (similar to the base-case, but including routine vaccination only). Vaccines were assumed to protect against disease for 10 years, with 50% efficacy.

Findings: The base-case scenario would prevent 44·0 million (95% uncertainty range 37·2-51·6) tuberculosis cases and 5·0 million (4·6-5·4) tuberculosis deaths before 2050, compared with equivalent estimates of cases and deaths that would be predicted to occur before 2050 with no new vaccine introduction (the baseline scenario). The accelerated scale-up scenario would prevent 65·5 million (55·6-76·0) cases and 7·9 million (7·3-8·5) deaths before 2050, relative to baseline. The routine-only scenario would prevent 8·8 million (95% uncertainty range 7·6-10·1) cases and 1·1 million (0·9-1·2) deaths before 2050, relative to baseline.

Interpretation: Our results suggest novel tuberculosis vaccines could have substantial impact, which will vary depending on delivery strategy. Including a one-off vaccination campaign will be crucial for rapid impact. Accelerated introduction-at a pace similar to that seen for COVID-19 vaccines-would increase the number of lives saved before 2050 by around 60%. Investment is required to support vaccine development, manufacturing, prompt introduction, and scale-up.

Funding: WHO (2020/985800-0).

Translations: For the French, Spanish, Italian and Dutch translations of the abstract see Supplementary Materials section.

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Conflict of interest statement

Declaration of interests SM reports employment by the International AIDS Vaccine Initiative, a non-profit product development partnership supporting the access-oriented development of vaccines for several disease areas, including tuberculosis, and grant funding from WHO. MJ is funded by the Bill & Melinda Gates Foundation, Gavi the Vaccine Alliance, the UK Research Institute, the National Institute for Health Research, the European Commission, and the Wellcome Trust, and reports leadership or fiduciary roles in the board, society, committee, or advocacy groups for WHO and Gavi. RCH reports employment by Sanofi Pasteur, unrelated to tuberculosis and outside the submitted work. NAM received consulting fees from The Global Fund to Fight AIDS, Tuberculosis and Malaria and WHO, and reports funding to their institution from the US Centers for Disease Control and Prevention, the Gates Foundation, the National Institute of Health, and the US Council of State and Territorial Epidemiologists. RGW is funded for other work by the Wellcome Trust (218261/Z/19/Z), the National Institute of Health (1R01AI147321–01), EDCTP (RIA208D-2505B), the UK's Medical Research Council (CCF17–7779 via SET Bloomsbury), the Economic and Social Research Council (ES/P008011/1), the Gates Foundation (OPP1084276, OPP1135288, and INV-001754), and WHO. All other authors declare no competing interests.

Figures

Figure 1
Figure 1
Assumed cumulative number of countries introducing the novel vaccine by year for the base-case and routine-only scenarios Base-case assumes introduction of routine vaccination for those aged 9 years and one-off vaccination for those aged 10 years and older. Routine-only assumes introduction of routine vaccination among those aged 9 years only. The earliest vaccine introduction occurs in 2028 and the latest in 2047. See appendix 5 (pp 26–33) for full details.
Figure 2
Figure 2
Cumulative cases, treatments, and deaths averted between vaccine introduction and 2050, and incidence and mortality rate reductions in 2050 for the vaccine for adolescents and adults with varying delivery scenarios (50% efficacy vaccine, medium coverage, 10-year duration of protection), by WHO region, WHO tuberculosis burden level, and World Bank income group, expressed relative to a baseline scenario with no new vaccine Cumulative cases, treatments, and deaths averted are calculated for each vaccine scenario compared with the estimated number predicted by 2050 with the status quo no-new-vaccine baseline. Incidence and mortality rate reductions are calculated relative to the incidence and mortality rate predicted in 2050 by the status quo no-new-vaccine baseline. Base-case scenario: routine vaccination of those aged 9 years and a one-off campaign for those aged 10 years and older, introduced in country-specific years between 2028 and 2047 and scaled up over 5 years. Accelerated scale-up scenario: routine vaccination of those aged 9 years and a one-off campaign for those aged 10 years and older, introduced in 2025 and scaled up instantly in all countries. Routine-only scenario: routine vaccination of those aged 9 years, introduced in country-specific years between 2028 and 2047 and scaled up over 5 years.
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References

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