Poliovirus circulation in the WHO European region, 2015-2022: a review of data from WHO's three core poliovirus surveillance systems

Background: The Global Polio Eradication Initiative (GPEI) has drastically reduced the global incidence of poliomyelitis since its launch in 1988 thanks to effective vaccines and strong global surveillance systems. However, detections of wild-type as well as vaccine-derived poliovirus (VDPV) still occur, also in the WHO European Region. This study aims to describe the poliovirus detection via the acute flaccid paralysis (AFP), clinical enterovirus, and environmental surveillance systems.

Methods: In this study, we review data from annual reports from 2015 to 2022 from the World Health Organization (WHO)'s three core poliovirus surveillance systems in place in the WHO European Region: AFP, clinical enterovirus, and environmental surveillance systems.

Findings: A total of 4324 reported samples were found positive for poliovirus: 477 from AFP surveillance, 394 from clinical surveillance and 3453 from environmental surveillance. Of these, 366 were VDPV, 3952 vaccine strains, and 6 were wild-type poliovirus. 709 were identified as type 1, 399 as type 2, and 1944 type 3, while 1272 samples contained more than one type. Temporal and spatial association of positive environmental samples with positive samples from AFP or clinical enterovirus surveillance was found in only eight countries.

Interpretation: Analysis of poliovirus-positive samples from AFP, clinical enterovirus, and environmental surveillance revealed that type 3 poliovirus was the most prevalent type detected. Most poliovirus-positive samples were identified as vaccine strains. No information on sequences was available.

Funding: This study was funded by WHO Regional Office for Europe and received financial support from the Bill and Melinda Gates Foundation.