Abstract
Certification of global eradication of indigenous wild poliovirus type 2 occurred in 2015 and of type 3 in 2019. Since the launch of the Global Polio Eradication Initiative (GPEI) in 1988 and broad use of live, attenuated oral poliovirus vaccine (OPV), the number of wild poliovirus cases has declined >99.99% (1). Genetically divergent vaccine-derived poliovirus* (VDPV) strains can emerge during vaccine use and spread in underimmunized populations, becoming circulating VDPV (cVDPV) strains, and resulting in outbreaks of paralytic poliomyelitis.† In April 2016, all oral polio vaccination switched from trivalent OPV (tOPV; containing vaccine virus types 1, 2, and 3) to bivalent OPV (bOPV; containing types 1 and 3) (2). Monovalent type 2 OPV (mOPV2) is used in response campaigns to control type 2 cVDPV (cVDPV2) outbreaks. This report presents data on cVDPV outbreaks detected during January 2018-June 2019 (as of September 30, 2019). Compared with January 2017-June 2018 (3), the number of reported cVDPV outbreaks more than tripled, from nine to 29; 25 (86%) of the outbreaks were caused by cVDPV2. The increase in the number of outbreaks in 2019 resulted from VDPV2 both inside and outside of mOPV2 response areas. GPEI is planning future use of a novel type 2 OPV, stabilized to decrease the likelihood of reversion to neurovirulence. However, all countries must maintain high population immunity to decrease the risk for cVDPV emergence. Cessation of all OPV use after certification of polio eradication will eliminate the risk for VDPV emergence.
Highlights
January 2018–June 2019; 25 (86%) outbreaks were cVDPV2 emergences, 18 (72%) of which were detected during the first half of 2019 in Central and Western Africa. cVDPV2 cases primarily occurred in type 2-naïve children who were born after the switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) and who were at high risk because they were born in areas with chronically low routine and supplementary polio immunization coverage
International cVDPV2 spread of JIS-1 from Nigeria to Benin, Cameroon, Ghana, and Niger, and of BAN-1 from Somalia to Ethiopia suggests that multiple mOPV2 responses after detection in each of the countries were of insufficient quality, delayed, or too limited in scope to prevent further spread that, in some cases, led to international transmission
Following the synchronized switch from trivalent oral poliovirus vaccine to bivalent oral poliovirus vaccine in 2016, transmission of type 2 Circulating vaccine-derived polioviruses (cVDPVs) was detected in 12 countries in Africa and in China
Summary
Update on Vaccine-Derived Poliovirus Outbreaks — Worldwide, January 2018–June 2019. Jaume Jorba, PhD1; Ousmane M. This report presents data on cVDPV outbreaks detected during January 2018–June 2019 (as of September 30, 2019). Compared with January 2017–June 2018 (3), the number of reported cVDPV outbreaks more than tripled, from nine to. Cases and environmental surveillance (testing of sewage samples for poliovirus) continued to be detected from the previously reported Papua New Guinea outbreak (4) (Table); the AFP. A new cVDPV1 outbreak was reported in Myanmar; the first patient had paralysis onset in May 2019, and the most recent case occurred in August 2019. A new cVDPV1 outbreak of one case was reported in Indonesia with paralysis onset in November 2018. During January 2018–June 2019, 25 cVDPV2 outbreaks were reported in 13 countries (Table). Number of circulating vaccine-derived poliovirus (cVDPV) isolates detected, by serotype, source, and other selected characteristics — worldwide, January 2018–June 2019
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