In an update on the polio ( circulating vaccine-derived poliovirus type 2–cVDPV2) outbreak in Syria, the World Health Organization (WHO) reports there is evidence of genetic linkage among three isolates of type-2 vaccine-derived polioviruses (VDPV2) isolated in the stool specimens of two acute flaccid paralysis (AFP) cases with dates of onset of paralysis on 5 March and 6 May 2017, and the contact specimen of an AFP case collected on 17 April 2017.
Since the confirmation of the first VDPV2 during May 2017, AFP surveillance has been intensified in the Governorate, especially in the Al Mayadeen district. As of 6 June 2017, a total of 58 AFP cases have been reported from the Governorate this year. In addition to the two cases that have tested positive for VDPV2, a further 11 have tested negative for polioviruses, with the remaining samples being under process in the laboratories or being transported to the laboratories.
Although access for vaccination is compromised due to prevailing insecurity in Deir Al Zour, the Governorate has been partially reached by several vaccination campaigns against polio and other vaccine-preventable diseases since the beginning of 2016. Most recently, two campaigns have been conducted in March and April 2017 using bivalent oral polio vaccine (bOPV). The most recent full trivalent oral polio vaccine (tOPV) round was conducted in October 2015; while tOPV rounds conducted in the first four months of 2016 only reached part of the target population of the Deir Al Zour Governorate. It is pertinent to mention that Syrian Arab Republic introduced two doses of inactivated polio vaccine (IPV) in the routine infant immunization schedule in 2008. Syrian Arab Republic switched from tOPV to bOPV for routine immunization on 1 May 2016.
Democratic Republic of the Congo
In the Democratic Republic of the Congo (DRC), two separate circulating vaccine-derived poliovirus type 2s (cVDPV2s) have been confirmed. The first cVDPV2 strain has been isolated from two acute flaccid paralysis (AFP) cases from two districts in Haut-Lomami province, with onset of paralysis on 20 February and 8 March 2017. The second cVDPV2 strain has been isolated from Maniema province, from two AFP cases (with onset of paralysis on 18 April and 8 May 2017) and a healthy contact in the community.
Outbreak response plans are currently being finalized, consisting of strengthening surveillance, including active case searching for additional cases of AFP, and supplementary immunization activities (SIAs) with monovalent oral polio vaccine type 2 (mOPV2), in line with internationally-agreed outbreak response protocols.
WHO assesses the risk of further national spread of these strains to be high, and the risk of international spread to be medium.