Notes from the Field: Circulating Vaccine-Derived Poliovirus Outbreaks - Five Countries, 2014-2015.

Notes from the Field: Circulating Vaccine-Derived Poliovirus Outbreaks - Five Countries, 2014-2015. MMWR Morb Mortal Wkly Rep. 2016;65(5):128-9 Authors: Morales M, Nnadi CD, Tangermann RH, Wassilak SG Abstract In 2015, wild poliovirus (WPV) transmission was identified in only Afghanistan and Pakistan (1). The widespread use of live, attenuated oral poliovirus vaccine (OPV) has been key in polio eradication efforts. However, OPV use, particularly in areas with low vaccination coverage, is associated with the low risk for emergence of vaccine-derived polioviruses (VDPV), which can cause paralysis (2). VDPVs vary genetically from vaccine viruses and can cause outbreaks in areas with low vaccination coverage. Circulating VDPVs (cVDPVs) are VDPVs in confirmed outbreaks. Single VDPVs for which the origin cannot be determined are classified as ambiguous (aVDPVs), which can also cause paralysis. Among the three types of WPV, type 2 has been declared to be eradicated. More than 90% of cVDPV cases have been caused by type 2 cVDPVs (cVDPV2). Therefore, in April 2016, all OPV-using countries of the world are discontinuing use of type 2 Sabin vaccine by simultaneously switching from trivalent OPV (types 1, 2, and 3) to bivalent OPV (types 1 and 3) for routine and supplementary immunization. The World Health Organization recently broadened the definition of cVDPVs to include any VDPV with genetic evidence of prolonged transmission (i.e., >1.5 y...
Source: MMWR Morb Mortal Wkl... - Category: Epidemiology Authors: Tags: MMWR Morb Mortal Wkly Rep Source Type: research