The EU-WISH International Workshop & Consortium Meeting took place at University College Dublin in early September 2025, representing a key milestone for the Joint Action. The event brought together over 150 experts and stakeholders from across Europe and beyond to discuss priorities for wastewater-based public health surveillance.

This meeting report details all sessions held over the three days, revisits the prioritisation outcomes, and presents a summary of sessions dedicated to exploring how wastewater data can inform public health decision-making for the first time. This includes challenges related to data integration, comparability, and cross-border coordination.

Day 1 of the workshop focused on prioritization of the wastewater surveillance targets for respiratory viruses and emerging pathogens, antimicrobial resistance, poliovirus and non-polio enteroviruses, and for illicit drugs, chemical substances and health related biomarkers.

For Polio, the discussion topics included:

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1. Public health actions in response to vaccine-derived poliovirus (VDPV) detections in Europe
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2. Sampling strategies
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3. Advantages and disadvantages of cell culture and direct methods for detection of poliovirus in wastewater; Enterovirus prioritization.
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For each of these topics, the discussion between the participants of the breakout session arrived at aligned EU recommendations, which are provided in the table below.

1. Public health actions for VDPV

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• It was stressed that it is important to develop and implement a poliovirus preparedness plan 
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• It is essential to share wastewater derived poliovirus sequences with the World Health Organization (GPL network) to characterize and identify the virus  
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• It is important to ascertain which poliovirus strains are circulating
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2. Sampling strategy

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• It is recommended to sample wastewater treatment plants serving large populations preferably between 100.000 to 300.000 people
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• Sampling strategies should be country specific, i.e., the breakout session did not recommend detailed general sampling rules
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• A good balance between bigger and lower size sampling sites is seen as an added value
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• At risk populations include those with low vaccination coverage, those receiving a large influx of people from countries with low vaccination coverage and where vaccine-derived poliovirus is circulating
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• Composite, grab or passive samplers can be used for targeting smaller areas within the sewerage system
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• For grab samples, setting the sampling time at an adequate moment (when most people use a toilet) is the key to allow as good representativeness of the population as possible
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• The sampling site location and duration of site’s exploitation are even more important than the choice of the sampling frequency
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3. Adaptation of poliovirus lab protocol(s) 

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• External factors affecting the quality of the sample, e.g., heavy rainfall and chemicals that could act as potential inhibitors (e.g., fertilizers) should be taken into consideration 
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• Importance of having a process control such as mouse hepatitis virus, another enterovirus, or pepper mild mottle virus (PMMoV)
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• Differences in sequences from the same sample, if coming from cell culture or from direct PCR is a fact to know and consider 
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• Need to have guidelines more adapted to EU context (CDC guidelines as a good alternative) 
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• No consensus with regards to prioritization of non-polio enterovirus D68 and/or A71
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• Vaccine derived poliovirus (VDPV) surveillance is prioritized over non-polio enterovirus D68 and/or A71
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The above outcomes from the Day1 prioritization workshop can be found here