Evidence required to evaluate the use of bacteriologically confirmed asymptomatic tuberculosis disease as a primary endpoint in prevention of tuberculosis disease vaccine licensure trials

Current licensure trials of new vaccines to prevent tuberculosis disease use bacteriologically confirmed symptomatic tuberculosis disease as the primary endpoint. Globally, the incidence of symptomatic tuberculosis disease is low, making licensure trials large, long, and expensive. New data suggest that bacteriologically confirmed asymptomatic tuberculosis disease might occur more frequently than symptomatic tuberculosis disease. Therefore, if vaccines have efficacy against asymptomatic disease, tuberculosis vaccine licensure trials could include it in the primary endpoint, potentially leading to smaller or shorter trials. We describe the potential benefits and risks of this inclusion in the primary endpoint of tuberculosis vaccine licensure trials. We also simulate licensure trial endpoint accrual and summarise feedback from anonymous regulators and policy makers on the knowledge needed to consider this proposal and research studies needed to fill these evidence gaps. If bacteriologically confirmed asymptomatic tuberculosis disease could be included in the primary endpoint of tuberculosis disease licensure trials, it could lead to cheaper and more rapid tuberculosis vaccine development.