Polio this week as of 27 April 2016
Around the world, countries that remain vulnerable to polio are continuing to vaccinate children and build immunity, as shown in Jordan through this series of photographs.
The Trivalent to Bivalent Oral Polio Vaccine Switch
Between 17 April and 1 May, the type 2 component of the oral polio vaccine (OPV) is being removed from use through a globally synchronized switch from the trivalent to bivalent oral polio vaccine. This is the first stage of objective 2 of the Polio Eradication and Endgame Strategic Plan 2013-2018 to withdraw OPV in a phased manner starting with the type 2 component following the eradication of wild poliovirus type 2 in September 2015.
Follow a live update of which countries have undergone the switch here. Learn more about why the switch is such an important part of ensuring a polio-free world through this series of videos.
The following indicators are being carefully tracked to ensure the switch goes smoothly. As of 25 April:
75 of 155 (48%) countries and territories have stopped using the trivalent oral polio vaccine.
Independent monitoring to ensure the switch goes smoothly has begun in 63 countries.
The National Validation Committee has received switch monitoring data from four countries: Tuvalu, Rwanda, Sao Tome and Burundi.
The WHO Regional Office has received the National Validation Report from one country: Tuvalu.
Wild poliovirus type 1 and Circulating vaccine-derived poliovirus cases
Total in 2015
- in endemic countries
- in non-endemic countries
Case breakdown by country
Total in 2015
Onset of paralysis of most recent case
NA: onset of paralysis in most recent case is prior to 2015. Figures exclude non-AFP sources. Madagascar, Ukraine and Lao PDR cVDPV1, all others cVDPV2. cVDPV definition: see document "Reporting and classification of vaccine-derived polioviruses" at http://www.polioeradication.org/Portals/0/Document/Resources/VDPV_ReportingClassification.pdf. Implementation as of 15 August 2015.
No cases of circulating vaccine-derived poliovirus type 1 (cVDPV1) have been reported in 2016. The most recent case had onset of paralysis on 22 August 2015 from Sud-Ouest region. The total number of cVDPV1 cases for 2015 remains 10.
The third Outbreak Response Assessment in Madagascar found that the surveillance system is not yet strong enough to conclude that polio transmission has been interrupted. Thirty-nine high-risk districts have been identified to receive focused attention.
The 2015 cases are genetically linked to the case with onset of paralysis in September 2014, indicating prolonged and widespread circulation of the virus. Learn more about vaccine derived polioviruses here.
National Immunization Days (NIDs) took place from 11 to 15 April, using trivalent oral polio vaccine (OPV) in preparation for the trivalent to bivalent OPV switch.
No cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) have been reported in 2016. The most recent case was isolated from a 16-month old child in Maungdaw, Rakhine, with onset of paralysis on 05 October. The total number of cVDPV2 cases in 2015 remains two.
Mop up activities took place in six townships in Rakhine state from 23 to 25 April, prior to the switch, using trivalent oral polio vaccine (OPV).
No wild poliovirus type 1 (WPV1) cases have been reported in 2016. No cases were reported in 2015. The most recent case had onset of paralysis on 24 July 2014 in Sumaila Local Government Area (LGA), southern Kano state.
No cases of type 2 circulating vaccine-derived poliovirus (cVDPV2) have been reported in 2016. The most recent case had onset of paralysis in Kwali Local Government Area (LGA), Federal Capital Territory (FCT) Abuja, with onset of paralysis on 16 May 2015; this is the only cVDPV2 case reported in Nigeria in 2015.
Vigilance must be maintained to ensure that all children are reached with polio vaccines and that surveillance systems remain alert to detect polioviruses.
Sub-National Immunization Days (SNIDs) are planned in the north of the country from 14 to 17 May using bivalent oral polio vaccine (bOPV).
No circulating vaccine-derived poliovirus type 1 (cVDPV1) cases have been reported in 2016. The most recent case had onset of paralysis on 07 July 2015 in the Zakarpatskaya oblast, in south-western Ukraine, bordering Romania, Hungary, Slovakia and Poland. The number of cVDPV1 cases reported in 2015 remains two.
Ukraine had been at particular risk of emergence of a cVDPV, due to very low vaccination coverage. Learn more about vaccine derived polioviruses here.
No circulating vaccine-derived poliovirus type 2 (cVDPV2) cases have been reported from Guinea in 2016. The most recent case was reported from Kankan district, with onset of paralysis on 14 December. The total number of cVDPV2 cases for 2015 remains seven. The 2015 cases are genetically linked to the case with onset in August 2014.
National Immunization Days (NIDs) took place in Benin, Burkina Faso, Cote d’Ivoire, Guinea, Liberia, Mali, Mauritania, Niger, Senegal and Sierra Leone in April using trivalent oral polio vaccine prior to the switch.
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