Figure 4. Relative odds of shedding vaccine poliovirus after challenge among individuals vaccinated with OPV compared with IPV.

Labeling as for Figure 2. The χ² test for heterogeneity among studies was significant for serotypes 1 and 3 (p-values<0.001, 0.79, and 0.01 for serotypes 1, 2, and 3, respectively) and for the overall odds ratio (p-value<0.001). *Ghendon et al. 1961 [17] compare vaccinated and unvaccinated children who were confirmed seropositive and seronegative, respectively.