Modeling the prevalence of @entity465 -associated long-term vaccine-derived XXXX excretors and the potential benefits of antiviral drugs.

@entity1 @entity9925 @entity281 @entity1200 @entity465
BACKGROUND: A small number of individuals with B-cell-related @entity1200 ( @entity1200 ) may exhibit long-term (prolonged or chronic) excretion of @entity465 -associated vaccine-derived polioviruses (iVDPVs) following infection with oral @entity9925 vaccine (OPV). These individuals pose a risk of live @entity9925 reintroduction into the population after global wild @entity9925 eradication and subsequent OPV cessation. Treatment with polio antiviral drugs may potentially stop excretion in some of these individuals and thus may reduce the future population risk. METHODS: We developed a discrete event simulation model to characterize the global prevalence of long-term iVDPV excretors based on the best available evidence. We explored the impact of different assumptions about the effectiveness of polio antiviral drugs and the fraction of long-term excretors identified and treated. RESULTS: Due to the rarity of long-term iVDPV excretion and limited data on the survival of PID @entity1 in developing countries, uncertainty remains about the current and future prevalence of long-term iVDPV excretors. While the model suggests only approximately 30 current excretors globally and a rapid decrease after OPV cessation, most of these excrete asymptomatically and remain undetected. The possibility that one or more PID @entity1 may continue to excrete iVDPVs for several years after OPV cessation represents a risk for reintroduction of live polioviruses after OPV cessation, particularly for middle-income countries. With the effectiveness of a single polio antiviral drug possibly as low as 40  % and no system in place to identify and treat asymptomatic excretors, the impact of passive use of a single polio antiviral drug to treat identified excretors appears limited. Higher drug effectiveness and active efforts to identify long-term excretors will dramatically increase the benefits of polio antiviral drugs. CONCLUSIONS: Efforts to develop a second polio antiviral compound to increase polio antiviral effectiveness and/or to maximize the identification and treatment of affected individuals represent important risk management opportunities for the polio endgame. Better data on the survival of PID  @entity1 in developing countries and more longitudinal data on their exposure to and recovery from OPV @entity281 would improve our understanding of the risks associated with iVDPV excretors and the benefits of further investments in polio antiviral drugs.
