Figure 3. Results from first 2 rounds of Wisconsin Wastewater Monitoring Program proficiency testing, including respiratory pathogens SARS-CoV-2, influenza A, influenza B, and RSV in study of implementation and early outcomes of laboratory proficiency testing program for National Wastewater Surveillance System, United States, 2024. A) Concentrations of pathogens reported by the laboratories participating in proficiency testing rounds 1 and 2. Each symbol represents 1 laboratory’s results from a single workflow, averaged over gene targets (if applicable) and replicates (n = 3 for both rounds). B) RSD (%) of pathogen concentrations reported from the replicates in panel A (n = 3). Shapes and colors denote different methods of wastewater concentration and extraction (Figure 1). Horizontal lines within boxes indicate median, top lines of each box indicate 75th percentiles, and bottom lines represents 25th percentiles. gc/L, gene copies per liter; RSD, relative standard deviation; RSV, respiratory syncytial virus.