**What do the risk estimates mean for leaders
of low-income countries?**

- The following chart uses a pull-down menu (on the right) to allow visualization of how the risks of an outbreak (defined explicitly in the manuscript as one or more paralytic polio cases) in low-income countries vary for different policy options over time.
- The chart shows the outbreak rate per year for a population of 100 million people (i.e., 100,000,000) using scientific notation (i.e., 1.3 E-4 means 0.00013 or alternatively 1.3 per 10,000).
- The analysis relates to conditions following successful global eradiction of wild polioviruses such that at the starting time (T0) no wild polioviruses are circulating.
- We assume that Supplemental Immunization Activities (SIAs), which to date have exclusively used OPV, are an option only when using OPV for routine immunization.
- For the condition of continued OPV use we show only the Containment Not Enforced option, because cVDPV risks dominate such that we obtain the same resutls with either option for containment.
- Since the risks of outbreaks from circulating vaccine-derived polioviruses (cVDPVs) depend on the quantification choice (i.e., based on confirmed cVDPVs or cVPDVs plus aVDPVs), we include both of these risk cases in the pull-down menus. We emphasize that all of the results shown in the charts include all risks characterized in the paper (i.e., those from cVDPVs, iVDPVs, unintentional and intentional releases, etc.), so the note on the figures about the cVDPV risk case only refers to how those risks are characterized.
- Since the population immunity level at T0 impacts the probability of cVDPV outbreaks, the paper includes 2 possibilities: Realistic Population Immunity (the base case, which assumes countries stop conducting SIAs and/or maintaining high population immunity 3 years prior to T0) and Maximum Population Immunity (which assumes a coordinated pulse or efforts that bring coverage in all areas up to more than 90% prior to T0).
- NOTE: The estimates of the probability of at least one outbreak during the first 6 years and first 20 years after (T0) only apply to a population of 100 million and a linear scaling approximation may not be appropriate (particularly for relatively larger annual outbreak rates).
- Please refer to the full paper for important technical details related to the assumptions.

Low-income countries (Select from pull down: Routine vaccine/SIAs or not/cVDPV risk case/Population Immunity at T0/Containment enforced or not):

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