Four countries reported vaccine-derived polio cases this week, according to the latest update from the Global Polio Eradication Initiative (GPEI).
The Democratic Republic of the Congo reported four cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) in Haut Lomami province, bringing the number of 2022 cases to 287. Yemen reported 1 cVDPV2 case in Alhudaidah, bringing its 2022 total to 161 cases, along with five cVDPV2-positive environmental samples—two in Alhudaidah and three in Aden.
Mozambique reported two cVDPV type 1 cases in Zambezia, after recording 21 cases in 2022. Madagascar reported one cVDPV1 case in Sava and eight cVDPV1-positive environmental samples in Analamanga. The country has reported 14 cVDPV1 cases for 2022.
Vaccination efforts
In other polio news, GPEI said approximately 585 million doses of the novel oral polio vaccine type 2 (nOPV2) have been administered to date under the World Health Organization's Emergency Use Listing procedure.
The vaccine is a modified version of the type 2 monovalent OPV that has been shown in clinical trials to provide comparable protection while being more genetically stable and less likely to be associated with the emergence of cVDPV2 in low-immunity settings.