Strategic Response to an Outbreak of Circulating Vaccine-Derived Poliovirus Type 2 — Syria, 2017–2018

• Published in: MMWR. Morbidity and mortality weekly report 2018-06, Vol.67 (24), p.690-694
• Main Authors: Mbaeyi, Chukwuma, Wadood, Zubair Mufti, Moran, Thomas, Ather, Fazal, Stehling-Ariza, Tasha, Nikulin, Joanna, Al Safadi, Mohammad, Iber, Jane, Zomahoun, Laurel, Abourshaid, Nidal, Pang, Hong, Collins, Nikki, Asghar, Humayun, Butt, Obaid ul Islam, Burns, Cara C., Ehrhardt, Derek, Sharaf, Magdi
• Format: Article
• Language: English
• Subjects: Child, Preschool; Disease Outbreaks - prevention & control; Female; Full Report; Humans; Infant; Male; Poliomyelitis - epidemiology; Poliomyelitis - prevention & control; Poliomyelitis - virology; Poliovirus Vaccine, Oral - adverse effects; Syria - epidemiology; Vaccination Coverage - statistics & numerical data
• ISSN: 0149-2195; 1545-861X
• DOI: 10.15585/mmwr.mm6724a5

Since the 1988 inception of the Global Polio Eradication Initiative (GPEI), progress toward interruption of wild poliovirus (WPV) transmission has occurred mostly through extensive use of oral poliovirus vaccine (OPV) in mass vaccination campaigns and through routine immunization services (1,2). However, because OPV contains live, attenuated virus, it carries the rare risk for reversion to neurovirulence. In areas with very low OPV coverage, prolonged transmission of vaccine-associated viruses can lead to the emergence of vaccine-derived polioviruses (VDPVs), which can cause outbreaks of paralytic poliomyelitis. Although WPV type 2 has not been detected since 1999, and was declared eradicated in 2015,* most VDPV outbreaks have been attributable to VDPV serotype 2 (VDPV2) (3,4). After the synchronized global switch from trivalent OPV (tOPV) (containing vaccine virus types 1, 2, and 3) to bivalent OPV (bOPV) (types 1 and 3) in April 2016 (5), GPEI regards any VDPV2 emergence as a public health emergency (6,7). During May-June 2017, VDPV2 was isolated from stool specimens from two children with acute flaccid paralysis (AFP) in Deir-ez-Zor governorate, Syria. The first isolate differed from Sabin vaccine virus by 22 nucleotides in the VP1 coding region (903 nucleotides). Genetic sequence analysis linked the two cases, confirming an outbreak of circulating VDPV2 (cVDPV2). Poliovirus surveillance activities were intensified, and three rounds of vaccination campaigns, aimed at children aged