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

BackgroundTuberculosis is a leading infectious cause of death worldwide. Novel vaccines will be required to reach global targets and reverse setbacks from the COVID-19 pandemic. We estimated the impact of novel tuberculosis vaccines in low- and middle-income countries (LMICs) under alternative delivery scenarios. MethodsWe calibrated a tuberculosis model to 105 LMICs (93% of global tuberculosis incidence). Vaccine scenarios were implemented as Basecase: routine vaccination of 9-year-olds and a one-time vaccination campaign for ages [≥]10 with country-specific introduction between 2028-2047 and 5-year scale-up to target coverage; Accelerated Scale-up: as Basecase, but all countries introducing in 2025 with instant scale-up; and Routine Only: as Basecase, but routine vaccination only. Vaccines protected against disease for 10-years, with 50% efficacy. FindingsThe Basecase scenario prevented 44.0 (95% uncertainty range=37.2-51.6) million tuberculosis cases, and 5.0 (4.6-5.4) million tuberculosis deaths before 2050, including 2.2 million in the WHO South-East Asian region. The Accelerated Scale-up scenario prevented 65.5 (55.6-76.0) million cases and 7.9 (7.3-8.5) million deaths before 2050. The Routine Only scenario prevented 8.8 (7.6-10.1) million cases and 1.1 (0.9-1.2) million deaths before 2050. InterpretationsNovel tuberculosis vaccines could have substantial impact, which will vary depending on delivery strategy. Including a campaign will be crucial for rapid impact. Accelerated introduction, more similar to the pace of COVID-19 vaccines, could increase lives saved by around 60%. Investment is required to support vaccine development, manufacturing, prompt introduction and scale-up. FundingWHO (2020/985800-0)