P.D. van Helden, E.G. Hoal/Comparative Immunology, Microbiology and Infectious Diseases 36(2013 )287-294 Protected Vaccinate Partial protection Vaccine Active TB case Infecte accine Exposed Boost not Not protected Protecte Immune Active TB Therapeutic ystem I factors not shown here are the type of vaccine used at any given a at any given administration, the timing involved or the dose The figure also there there is no active disease. These matters are discussed in the text of people. This variability may apply similarly to different as disease. However, in the case of possums, an alien species nimal species in New Zealand for example, we may want a vaccine that Once we have some idea of vaccine protection, we can presents transmission and not be concerned about the indi sk the next question: what coverage will be needed for the vidual animal and its health status. Our need for protection vaccination to work under the different scenarios? This will in wildlife and or domestic stock may differ, as might our also depend on the prevalence of disease and ultimate goal approach to maintenance hosts or spill-over species. Thus, of vaccination, which in turn will depend on its efficacy we may aim at eradication under some scenarios should a for a given individual, herd or species. It is highly unlike vaccine confer 100% protection, or control, which would b that we will achieve 100% coverage or protection, but at a an improvement over the current situation. The cost of vac certain point we will probably be able to attain adequate ination would have to be considered against potential gain herd immunity to reduce prevalence incidence and achieve in the DACYs in humans, agricultural losses in livestock or control or perhaps even eradication. ecosystem 10. Goal of vaccination 11. Will a new vaccine merely shift the population structure of mycobacteria? The goal or aim of vaccination may be quite different for different species. For humans, a highly mobile species, we We know that the relative proportion of certain strains would optimally want a vaccine that offers individuals full of M tuberculosis are waxing or waning in different regions protection against disease and preferably infection as well of the globe 59]. furthermore, there is good evidence toP.D. van Helden, E.G. Hoal / Comparative Immunology, Microbiology and Infectious Diseases 36 (2013) 287–294 291 Fig. 1. A simplified scheme illustrating key points to consider for vaccination against TB. It is assumed here that at least some protection is conferred by vaccination. Additional factors not shown here are the type of vaccine used at any given administration, the timing involved, or the dose. The figure also does not illustrate the complication of a post-exposure vaccination event, where there is no active disease. These matters are discussed in the text. of people. This variability may apply similarly to different animal species. Once we have some idea of vaccine protection, we can ask the next question: what coverage will be needed for the vaccination to work under the different scenarios? This will also depend on the prevalence of disease and ultimate goal of vaccination, which in turn will depend on its efficacy for a given individual, herd or species. It is highly unlikely that we will achieve 100% coverage or protection, but at a certain point we will probably be able to attain adequate herd immunity to reduce prevalence incidence and achieve control or perhaps even eradication. 10. Goal of vaccination The goal or aim of vaccination may be quite different for different species. For humans, a highly mobile species, we would optimally want a vaccine that offers individuals full protection against disease and preferably infection as well asdisease.However,inthe case ofpossums, analienspecies in New Zealand for example, we may want a vaccine that presents transmission and not be concerned aboutthe indi￾vidual animal and its health status. Our need for protection in wildlife and/or domestic stock may differ, as might our approach to maintenance hosts or spill-over species. Thus, we may aim at eradication under some scenarios should a vaccine confer 100% protection, or control, which would be an improvement over the current situation. The cost of vac￾cination would have to be considered against potential gain in the DACYs in humans, agricultural losses in livestock or ecosystem damage in wildlife. 11. Will a new vaccine merely shift the population structure of mycobacteria? We know that the relative proportion of certain strains of M. tuberculosis are waxing or waning in different regions of the globe [59]. Furthermore, there is good evidence to