Fig. 4
From: The risk of type 2 oral polio vaccine use in post-cessation outbreak response
Position of the 50% separatrix line as number of IPV doses in routine immunization varies, at constant λ = 60 days, g = 0.5, c = 1. The dashed and solid lines, respectively, indicate N IPV = 0 or 1, and the cyan, red, gray, and black lines, respectively, indicate R 0f values of 3, 2, 1.5, and 1.2. The thin black dashed box indicates migration rates that are preferred by a calibration to a single traveling WPV1 outbreak in the region, in 2008. Under the assumptions made in this model regarding the population-level effects of IPV dosing, an additional dose of IPV in routine immunization in the cohort born after cessation provides a strong mitigating effect on the risk of OPV2 survival and circulation at low R 0; the mitigating effect declines as the R 0 of the reverted virus increases