Circulating Vaccine Derived Poliovirus and the polio eradication endgame

The world is now in the 24 year of the Global Polio Eradication Initiative. Halfway through that initiative in 2000, the island of Hispaniola saw an outbreak of vaccine derived poliovirus [1]. The implications of this outbreak and multiple subsequent isolations of Sabin strains that are estimated to have circulated in communities for a year or more are now causing a reconsideration of the optimal way to achieve polio eradication. These circulating vaccine derived polio viruses, cVDPV, in many cases have regained the virulence and capacity to cause paralytic disease that we associate with wild-type poliovirus (WPV) strains. They, with the prolonged poliovirus vaccine virus shedding seen in some immunodeficient children, iVDPV, have uncovered a serious risk to polio eradication using OPV as our sole weapon.