Modelling the health and economic impacts ofM72/AS01E vaccination and BCG-revaccination: Estimates for South Africa

Tom Sumner; Rebecca A Clark; Christinah Mukandavire; Allison Portnoy; Chathika K Weerasuriya; Roel Bakker; Danny Scarponi; Mark Hatherill; Nicolas A Menzies; Richard G White

doi:10.1016/j.vaccine.2024.01.072

Modelling the health and economic impacts ofM72/AS01_E vaccination and BCG-revaccination: Estimates for South Africa

Vaccine. 2024 Feb 27;42(6):1311-1318. doi: 10.1016/j.vaccine.2024.01.072. Epub 2024 Feb 2.

Affiliations

¹ TB Modelling Group and TB Centre, London School of Hygiene and Tropical Medicine, United Kingdom; Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom. Electronic address: tom.sumner@lshtm.ac.uk.
² TB Modelling Group and TB Centre, London School of Hygiene and Tropical Medicine, United Kingdom; Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom; Vaccine Centre, London School of Hygiene and Tropical Medicine, United Kingdom.
³ TB Modelling Group and TB Centre, London School of Hygiene and Tropical Medicine, United Kingdom; Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom.
⁴ Department of Global Health, Boston University School of Public Health, Boston, USA; Center for Health Decision Science, Harvard T.H. Chan School of Public Health, Boston, USA.
⁵ TB Modelling Group and TB Centre, London School of Hygiene and Tropical Medicine, United Kingdom; Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom; KNCV Tuberculosis Foundation, USA.
⁶ South African Tuberculosis Vaccine Initiative, Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, South Africa.
⁷ Center for Health Decision Science, Harvard T.H. Chan School of Public Health, Boston, USA; Department of Global Health and Population, Harvard T.H. Chan School of Public Health, USA.

PMID: 38307747
DOI: 10.1016/j.vaccine.2024.01.072

Abstract

Background: Tuberculosis remains a major public health problem in South Africa, with an estimated 300,000 cases and 55,000 deaths in 2021. New tuberculosis vaccines could play an important role in reducing this burden. Phase IIb trials have suggested efficacy of the M72/AS01_E vaccine candidate and BCG-revaccination. The potential population impact of these vaccines is unknown.

Methods: We used an age-stratified transmission model of tuberculosis, calibrated to epidemiological data from South Africa, to estimate the potential health and economic impact of M72/AS01_E vaccination and BCG-revaccination. We simulated M72/AS01_E vaccination scenarios over the period 2030-2050 and BCG-revaccination scenarios over the period 2025-2050. We explored a range of product characteristics and delivery strategies. We calculated reductions in tuberculosis cases and deaths and costs and cost-effectiveness from health-system and societal perspectives.

Findings: M72/AS01_E vaccination may have a larger impact than BCG-revaccination, averting approximately 80% more cases and deaths by 2050. Both vaccines were found to be cost-effective or cost saving (compared to no new vaccine) across a range of vaccine characteristics and delivery strategies from both the health system and societal perspective. The impact of M72/AS01_E is dependent on the assumed efficacy of the vaccine in uninfected individuals. Extending BCG-revaccination to HIV-infected individuals on ART increased health impact by approximately 15%, but increased health system costs by approximately 70%.

Interpretation: Our results show that M72/AS01_E vaccination or BCG-revaccination could be cost-effective in South Africa. However, there is considerable uncertainty in the estimated impact and costs due to uncertainty in vaccine characteristics and the choice of delivery strategy.

Funding: This work was funded by the Bill & Melinda Gates Foundation (INV-001754). This work used the Cirrus UK National Tier-2 HPC Service at EPCC (https://www.cirrus.ac.uk) funded by the University of Edinburgh and EPSRC (EP/P020267/1).

Keywords: BCG; Cost-effectiveness; M72; Modelling; South Africa; Tuberculosis; Vaccination.

MeSH terms

BCG Vaccine*
Humans
Immunization, Secondary
South Africa
Tuberculosis* / prevention & control
Vaccination

Substances

BCG Vaccine