Fig. 2: Compartmental models to accommodate the description of vaccines providing PoD by acting on specific routes to disease.

A (Top left): Venn diagram sketching the seven vaccine types contemplated in the study, as a function of the routes to disease they are assumed to protect against: primary TB (model 1), TB upon re-infection (model 2) or endogenous reactivation of LTBI (model 3). Combinations of these mechanisms yield models 4–7, which describe vaccines that are able to halt two (models 4, 5 and 6), or all three routes to disease at once. Each region of the Venn diagram corresponds to a value of the discrete index \(i\in \{{{{{\mathrm{1,2}}}}},\ldots,7\}\). Beside the diagram, we show the compartmental descriptions of each vaccine type. In each of the seven models, a vaccine arm is included in parallel to the placebo arm, that defines the disease dynamics of the vaccinated individuals who are protected against developing disease through the corresponding routes. B Maximum fraction of preventable cases by each vaccine, considering the mechanisms of protection present in each case. Source data are provided as a Source Data file.