Pre-publication version of Water Research Foundation inter laboratory methods comparison now available
November 19 webinar anticipated
A pre-publication version of the Water Research Foundation (WRF) 5089 inter laboratory methods comparison is now uploaded onto medRxiv (and available to you at https://www.medrxiv.org/content/10.1101/2020.11.02.20221622v1.)
Truscell Technologies has posted this pre-publication version.
https://www.medrxiv.org/content/10.1101/2020.11.02.20221622v1
The Abstract reads:
In response to COVID-19, the international water community rapidly developed methods to quantify the SARS-CoV-2 genetic signal in untreated wastewater. Wastewater surveillance using such methods has the potential to complement clinical testing in assessing community health. This interlaboratory assessment evaluated the reproducibility and sensitivity of 36 standard operating procedures (SOPs), divided into eight method groups based on sample concentration approach and whether solids were removed. Two raw wastewater samples were collected in August 2020, amended with a matrix spike (betacoronavirus OC43), and distributed to 32 laboratories across the U.S. Replicate samples analyzed in accordance with the project’s quality assurance plan showed high reproducibility across the 36 SOPs: 80% of the recovery-corrected results fell within a band of +/- 1.15-log10 genome copies/L with higher reproducibility observed within a single SOP (standard deviation of 0.13-log10). The inclusion of a solids removal step and the selection of a concentration method did not show a clear, systematic impact on the recovery-corrected results. Other methodological variations (e.g., pasteurization, primer set selection, and use of RT-qPCR or RT-dPCR platforms) generally resulted in small differences compared to other sources of variability. These findings suggest that a variety of methods are capable of producing reproducible results, though the same SOP or laboratory should be selected to track SARS-CoV-2 trends at a given facility. The methods showed a 7-log10 range of recovery efficiency and limit of detection highlighting the importance of recovery correction and the need to consider method sensitivity when selecting methods for wastewater surveillance.
Six conclusions read:
• A nationwide interlaboratory comparison of methods for the quantification of SARS-CoV-2 genetic signal in wastewater showed a high degree of reproducibility. 80% of the results from eight method groups (36 different methods) fell within a band of approximately +/- 1-log GC/L.
• Recovery-corrected results did not show a systematic impact from solids removal or concentration method used. Additional methods steps that were evaluated (e.g., pasteurization, primer set selection, and PCR platform) generally resulted in small differences compared to other sources of variability.
• Factors leading to greater interlaboratory reproducibility include a) the relative insensitivity of the findings to methodological differences, b) the implementation of strict QA/QC requirements, c) the use of a quality assurance project plan to normalize the findings and account for important sources of variability, and d) implementing a shared SOP among different laboratories.
• The findings support the use of wastewater surveillance for tracking trends in the concentrations of SARS-CoV-2 within communities. They also highlight methodological challenges related to modeling incidence and prevalence.
• Additional metrics should be used to select the best methods for future efforts including method sensitivity, cost, equipment requirements, and simplicity.
Thirty-two laboratories participated, of which 17 are academic, 6 commercial, 4 government, 3 utility, and 2 manufacturer. Participating labs are located in AZ (1), CA (5), CO (1), FL (2), LA (1), MD (1), ME (1), MI (1), MO (2), NE (2), NV (1), NJ (1), NY (3), OH (2), OR (1), TN (1), WI (3), UT (2), VA (1).
I anticipate webinar for WRF subscribers soon, likely be on November 19th.