What do the risk estimates mean for leaders
of lower middle-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 lower middle-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
- 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
Lower middle-income countries (Select from pull down: Routine vaccine/SIAs
or not/cVDPV risk case/Population Immunity at T0/Containment
enforced or not):