Rapid risk assessment – Assessing the risk to public health of multiple detections of poliovirus in wastewater in the EU/EEA
Poliomyelitis (polio) is a highly infectious disease caused by polioviruses, which can be prevented by vaccination. Polioviruses can be transmitted easily and silently across wide geographic areas. Most infected people do not develop symptoms, but if the virus invades the nervous system it can cause acute flaccid paralysis (AFP) within hours. Fewer than 1% of infections lead to irreversible paralysis. As the last indigenous case caused by an infection with wild poliovirus in Europe was reported in 1998, it has become a forgotten disease for most people in the European Union/European Economic Area (EU/EEA). The World Health Organization European Region (WHO Europe) was declared polio-free in June 2002, because of successful immunisation programmes, surveillance and outbreak response.
Executive summary
Between September and December 2024, four countries in the EU/EEA (Finland, Germany, Poland, and Spain) and the United Kingdom (UK) reported detections of a genetic cluster of circulating vaccine-derived poliovirus type 2 (cVDPV2) in sewage samples. This is the first time cVDPV2 has been detected in EU/EEA countries from environmental surveillance. No human cases of polio related to these detections of cVDPV2 have been reported in EU/EEA or the UK to date.
These recent importations and potential circulation of the virus pose a possible threat to public health within the EU/EEA and should be closely monitored, as they can lead to outbreaks in unvaccinated individuals. This risk assessment is the basis for ECDC recommendations to maintain high vaccination coverage, strengthen environmental and clinical surveillance and be vigilant to potential outbreaks of polio. ECDC encourages EU/EEA public health authorities to focus on the following actions:
- Achieve and sustain a very high uptake of three doses of IPV (inactivated poliovirus vaccine) (>90%) across communities, at subnational and national level, through the implementation of effective and timely routine childhood vaccination programmes.
- Design and rapidly deliver targeted catch-up programmes to identify and vaccinate individuals with incomplete or unknown vaccination status, following them until completed series. This is particularly important and urgent in communities and local areas of known suboptimal coverage or geographical clustering of the non- or under-vaccinated individuals in proximity of positive findings detected through environmental sampling.
- If polio cases occur, activate national poliomyelitis response plans (these plans should be updated, as needed, and field-tested) and alert clinicians, particularly paediatricians and neurologists, about AFP symptoms and polio risk.
- Review vaccination coverage data for the full IPV series at the lowest possible administrative level.
- Factors that lead to sub-optimal coverage in specific areas and population groups need to be explored to develop tailored, context-specific, culturally sensitive interventions to increase vaccination uptake.
- Conduct risk communication activities to highlight the importance of ensuring timely routine vaccination.
- Prioritise the offer of IPV to migrant populations in the EU/EEA with an unknown polio vaccination history.
- Ensure adequate stocks of IPV.
- Implement environmental surveillance for polioviruses according to WHO guidelines relevant also in polio-free countries with exclusive IPV use, assess environmental surveillance site performance and consider enhancing geographical coverage and sampling frequency, especially if detections have been made.
- Enhance Acute Flaccid Paralysis (AFP) syndromic and clinical enterovirus surveillance, where available, to ensure no infection in humans is missed.
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Detections of poliovirus in sewage samples require enhanced routine and catch-up vaccination and increased surveillance
Between September and December 2024, four countries in the EU/EEA (Finland, Germany, Poland, Spain) and the United Kingdom reported detections of circulating vaccine-derived poliovirus type 2 (cVDPV2) in sewage samples. This is the first time cVDPV2 has been detected in EU/EEA countries from environmental surveillance.