Vaccine-associated paralytic poliomyelitis in the postelimination era in Latin America and the Caribbean, 1992-2011

Abstract

The Americas interrupted the transmission of poliovirus in 1991; most Latin American and Caribbean (LAC) countries rely on the oral polio vaccine (OPV) to maintain elimination. We estimated the risk of vaccine-associated paralytic polio (VAPP) in LAC for 1992-2011. VAPP cases were identified using LAC's acute flaccid paralysis (AFP) surveillance system. VAPP was defined as any AFP case with residual paralysis 60 days following onset that did not have a clear alternative etiology and with isolation of vaccine-strain poliovirus. Recipient VAPP cases were defined as those with paralysis onset 4-40 days following OPV; cases meeting these criteria but with unknown residual paralysis were added. Nonrecipient VAPP cases were defined as those in individuals with an unknown vaccination status, those in individuals who received 0 doses, or those with paralysis onset outside the 4-40-day interval. Of 40 926 AFP cases reported in LAC from 1992-2011, we identified 72 recipient and 119 nonrecipient VAPP cases. The estimated risk of recipient VAPP was 1 case per 3.15 million newborns (95% confidence interval [CI], 1 case per 2.56-4.10 million newborns), and the estimated overall risk was 1 case per 1.19 million newborns (95% CI, 1 case per 1.04-1.39 million newborns). In this multicountry VAPP analysis in a postelimination period, we found that the risk of VAPP in LAC was lower than previously estimated.

Keywords: VAPP; global polio eradication; poliovirus; vaccine-associated paralytic polio.