Fig. 5.

Correlation of duration of shedding and the genetic divergence of iVDPVs. This figure demonstrates the relationship of percent genetic divergence of OPV strains at the VP1 region with the duration of shedding (for both calculated and reported definitions) of the iVDPV cases included in our analysis. Single and multivariable regressions were performed. Shedding duration and age were statistically associated with divergence and age — each additional year of shedding and age corresponded to an increase in the percent divergence by 0.72% and 0.08%, even after controlling for gender, presence of AFP, serotype, and survival status (p<3e⁻¹⁵; p< 0.00013). However, it is important to note that there are limitations in this analysis given the high mortality rate among case patients if the patient was still shedding at the time of death and the inherent bias in that shedding is only reported starting at case detection. Both these factors may have artificially shortened the measure for duration of shedding.