Fig. 1

Conceptual diagram of states for individuals in the population with respect to the development of various stages and types of long-term iVDPV excretion. Arrows between boxes indicate flows that represent PID disease and poliovirus infection progression, while trees within boxes represent branching between distinct pathways that imply one or more different downstream rates and probabilities. Notation (see also list of abbreviations): b, birth rate; d1, duration of infection for clinical PID patients with typical OPV infection; d2, duration of infection for prolonged excretors; d3, duration of infection for chronic excretors; Dgen, death rate for general population (by age); Dpid, death rate for clinical PID patients (by, PID category and receipt of effective treatment); eAVrate, effective rate of PAVD use; N, population size; OPVrate, combined primary (i.e., vaccination) and secondary OPV infection rate (by age, OPV use over time, diagnose status, and IVIG rate); Tchr, time to move from prolonged to chronic infection; Tonset, average time to onset of clinical PID; Tpro, time to move from OPV to prolonged infection; VAPPfrate(1, 2, and 3), VAPP fatality rate for PID patients (during OPV infection, prolonged excretion, and chronic excretion, respectively)