transmission models (Fig. 1a), susceptible individuals (S) are defined by their absence of immunoreactivity to TB—typically showing negative results to an Interferon-gamma-release assay19 (IGRA)—and get infected at a rate \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\beta$$\end{document}β. Here, IFNG is linked to tuberculosis.