In order to encourage the complete and open reporting of SARS-CoV-2 wastewater data, the RCN on Wastewater Surveillance for SARS-CoV-2 held a workshop in February 2021 to determine essential metadata that should be reported with wastewater surveillance research. Participants in the workshop were nominated or self-nominated and included representatives from academic research, government agencies, wastewater utilities, and private companies.
An overview of the workshop structure and major discussion points are summarized in this webpage. In addition, the complete workshop outcomes are now published in Environmental Science: Water Research & Technology and are accessible at this link: https://doi.org/10.1039/D1EW00235J
During the workshop, participants were divided into groups to discuss four different categories of SARS-CoV-2 wastewater surveillance data:
- Wastewater treatment plant & infrastructure data
- Sample collection data
- Sample processing data
- Target quantification data
The summary provided below includes major takeaways and outlooks from the student and postdoc discussion leaders assigned to each discussion group.
Major Discussion Takeaways
What is the minimum information needed to use the results reported in a study? This was the prompt used to guide deliberations in all groups, which was frequently revisited during discussion. Due to the diverse professional backgrounds represented in the breakout rooms (e.g., academics, public health practitioners, etc.), participants brought different perspectives on essential versus non-essential information depending on the final product, and this made for important discussions around useful but potentially non-universally available data, such as standard errors or endogenous wastewater controls (e.g. PMMoV and crAssphage).
Despite disagreements, researchers share a desire for improved reporting consistency. Throughout the group discussions, participants from various backgrounds and specialties worked together to determine which data should be deemed as essential. Using their scientific knowledge, as well as previous experiences, participants were able to advocate for different variables of data needed within different aspects of SARS-CoV-2 sewage monitoring efforts. Despite initial disagreement on which information is crucial for interpretation, there was an overwhelming desire to improve consistency in reporting, as well as advocacy for collaboration in various monitoring efforts.
Logistics of data acquisition and availability need to be considered. A challenge of consistent data reporting is the variable access to additional metadata that different researchers and practitioners are likely to experience. This can depend on both the state of existing infrastructure as well as the focus of the monitoring program. Examples include flow rates, which may be easily accessible and important data for monitoring at treatment facilities but difficult or impossible to obtain at upstream sewer monitoring locations. Determining standard data reporting recommendations therefore needs to maintain a certain amount of flexibility around such issues.
Comparison across studies requires complete reporting of sample processing protocols. The reporting of recovery controls was a major discussion point among participants. The type of recovery control used was considered incredibly important for comparison to other studies. The participants also indicated the necessity to include the complete protocol used for sample processing and report any changes made to the protocol. This is especially important for the current data being generated, as optimization and cross-study comparisons will be critical for promoting widespread use.
Outlook on Future WBE Studies
Don’t neglect the basics. Researchers should be sure to continue including the SARS-CoV-2 concentration back-calculated to unconcentrated sample basis (e.g., copies/L wastewater, copies/g solids), as that is the main objective of sample processing. Additionally, researchers must continue to follow important long-standing guidance for their quantification methods (e.g. qPCR, ddPCR), as quality control is different between these workflows. Finally, understanding negative results is just as important as positive results, making it critical to report samples that are below the limits of detection and quantification.
A call for open database tools. Future efforts should be directed to include all methods of sample processing in a single database, which would make it easier for researchers from across the world to access others’ methods and compare them to their own. The database should include the minimum metadata identified in this workshop, and remain flexible for additions and changes as wastewater SARS-CoV-2 surveillance continues to advance. Comparing the data generated from different methods can aid researchers in identifying the best possible methods for their samples and can serve as a resource to jump-start wastewater surveillance efforts under future public health emergencies. (To view a collection of current data sharing resources, click here: https://sites.nd.edu/rcn-wastewater-sarscov2/data-sharing-resources/)
Researchers should be encouraged to gather and report as much information as possible while processing methods and analysis tools continue to develop; however, there is still value in establishing a minimum data recommendation to enable more robust data interpretation. Through initiating a collaborative discussion on which data is considered essential for interpretation, we can encourage researchers to present crucial data in a similar and prioritized manner — thereby allowing for less ambiguous analysis and comparison of results captured from different monitoring efforts.
Workshop Summary written by: Mitham Al-faliti (Howard), Jill McClary-Gutierrez (Notre Dame), Lorelay Mendoza Grijalva (Stanford), and Fernando A. Roman, Jr. (UC Merced)