This is a summary, written by members of the CITF Secretariat, of:
Qiu Y, Yu J, Pabbaraju K, Lee BE, Gao T, Ashbolt NJ, Hrudey SE, Diggle M, Tipples G, Maal-Bared R, Pang X. Validating and optimizing the method for molecular detection and quantification of SARS-CoV-2 in wastewater. Sci Total Environ. 2022 Mar 15;812:151434. doi: 10.1016/j.scitotenv.2021.151434.
The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.
A CITF-funded study, published in Science of the Total Environment, reported a new method for molecular detection and quantification of SARS-CoV-2 in wastewater. Wastewater surveillance of SARS-CoV-2 has become a promising tool for estimating population-level changes in community infections, including the changing prevalence of SARS-CoV-2 infection. The study validated a molecular testing method by concentrating viruses from wastewater and detecting SARS-CoV-2 using the RT-qPCR assay. This method provides a useful tool for public health surveillance of COVID-19, supporting public health policy and actions for infection prevention and control. This study was led by Dr. Xiaoli Pang (University of Alberta and Alberta Precision Laboratories).
Key findings to optimize wastewater surveillance protocols:
- Wastewater pH adjustment for viral recovery: pH adjustment 5 of wastewater samples to 9.6-10 before solids removal and 7.0 after solids removal during wastewater concentration can facilitate the desorption of virus from solids and prevent viral RNA from degrading in high pH.
- Sample collection and storage temperature of 4 °C: to avoid freeze-thaw cycles in non-frozen and frozen wastewater samples, collection and storage at 4 °C storage is recommended to minimise degradation of SARS-CoV-2.
- Nucleic acid isolation kits for viral RNA extraction: among commercial nucleic acid extraction kits, the MagMAX-96 viral RNA isolation kit selected for this study provided both high recovery of viral RNA and automation saving time.
- One-step RT-qPCR: Compared to two-step RT-qPCR for SARS-CoV-2 detection, one-step RT-qPCR had improved sensitivity and required less time and effort.
Taken together, the study results validated a standard protocol for analytic procedures of one-step RT-qPCR-based detection of SARS-CoV-2 in wastewater. This protocol was implemented for targeted wastewater surveillance of a long-term care cohort participating in an immunity study supported by CITF funding.