Fig. 1

Decision tree model: overview of main screening strategies. HCWs healthcare workers, TB tuberculosis, LTBI latent TB infection, INH isoniazid. Path A Schematic overview of the basic strategies. For simplicity of display, the targeted screening strategy is divided into two branches. The upper branch of that strategy indicates that the highest-risk workers undergo annual screening; the lower branch indicates that lower-risk workers undergo post-exposure screening only. The two other main strategies (annual screening and post-exposure screening only) both apply a single screening protocol to all workers, regardless of their risk profile. Path B Subtree for annual screening. Workers with negative tests remain eligible for screening the following year. Path C Subtree for post-exposure screening. With this strategy, the steps that lead to testing for infection after exposure include the probability that exposure occurs, the probability that it leads to infection, the probability that it is recognised, and the probability that a worker presents for testing after being instructed to do so in the context of a recognised exposure. In the event that an exposure occurs but is not recognised, no testing takes place, and new infection is missed. Workers who are not tested, or who have negative tests, remain eligible for screening in case of subsequent exposure