([dagger]) After the global switch from trivalent oral poliovirus vaccine
(tOPV, containing Sabin types 1, 2, and 3) to bivalent OPV (bOPV, containing types 1 and 3), new emergences of cVDPV2 are identified by a three-letter country code, followed by three letters representing either state, province, or region, and a digit indicating the outbreak number in that state, province, or region.
Poliomyelitis prevention: recommendations for use of inactivated poliovirus vaccine and live oral poliovirus vaccine
. Pediatrics 1997; 99:300-5.
The WHO Global Action Plan to minimize poliovirus facility-associated risk after type-specific eradication of wild polioviruses and sequential cessation of oral poliovirus vaccine
use (GAPIII) (7) defines the biorisk management standards to be followed by facilities retaining poliovirus materials.
Among infants aged 1 year, the estimated global coverage with 3 doses of poliovirus vaccines (Pol3, mostly oral poliovirus vaccine
[OPV]) through routine immunization services was 85% in 2016 (the most recent year for which data are available).
Following the declaration of eradication of wild poliovirus (WPV) type 2 in September 2015, trivalent oral poliovirus vaccine
(tOPV) was withdrawn globally to reduce the risk for type 2 vaccine-derived poliovirus (VDPV2) transmission; all countries implemented a synchronized switch to bivalent OPV (type 1 and 3) in April 2016 (1,2).
Based on United Nations Children's Fund (UNICEF) and World Health Organization (WHO) estimates, national vaccination coverage among infants with 3 doses of oral poliovirus vaccine
(OPV [OPV3]) delivered through the routine immunization program was 72% in 2016, unchanged from 2014 and 2015 estimates (5).
The Global Action Plan to Minimize Poliovirus Facility-Associated Risk After Type-Specific Eradication of Wild Polioviruses and Sequential Cessation of Oral Poliovirus Vaccine
Use (GAPIII) (7), endorsed by the World Health Assembly in 2015, sets the stage for the implementation of containment work.
All countries with PV2 detected in 2017 (except Afghanistan) conducted immunization campaigns using monovalent oral poliovirus vaccine
type 2 (mOPV2) in response to cVDPV2 isolates detected in Pakistan and Nigeria.
Fifty-eight percent of children with polio had never received oral poliovirus vaccine
(OPV) either through routine or supplementary immunization (i.e., zero-dose children), and an additional 37% of children with polio had received [less than or equal to] 3 OPV doses.
This was the second cVDPV2 isolate identified in Borno in 2016; the first isolate was from an environmental sample collected in March 2016 in Maiduguri LGA which had prompted SIAs with monovalent oral poliovirus vaccine
type 2 (mOPV2) in May, June, and July (2).
This decrease was achieved primarily through the use of trivalent oral poliovirus vaccine
(tOPV), which contains types 1,2, and 3 live, attenuated polioviruses.
These polioviruses were detected approximately 4 months after April 25, 2016, when India officially ceased use of trivalent oral poliovirus vaccine
(tOPV), containing Sabin attenuated types 1, 2, and 3 polioviruses, and switched to bivalent OPV (bOPV), containing Sabin attenuated types 1 and 3 polioviruses (1).