Figure 2.

Timeline of global polio eradication efforts and study location for included papers the decade in which the last case of indigenous wild poliovirus was reported for each country is presented in different colours. Data from each country numbered were analysed by at least one study identified as meeting the inclusion criteria of our systematic review. Data on polio elimination certification year were sourced from the Global Polio Eradication Initiative. The figure was adapted from Our World in Data.⁶⁶