Last updated: November 10, 2022
Wastewater monitoring for COVID-19 involves testing for the presence of fragments of the virus (called SARS-CoV-2 RNA gene fragments). These fragments are shed by both asymptomatic and symptomatic individuals into wastewater. Monitoring wastewater can be a useful tool to monitor community transmission of COVID-19.
In Winter Term 1 2021/2022, UBC and BC Centre for Disease Control (BCCDC) established a partnership to conduct a 4-month pilot program to demonstrate this approach at two UBC student residences— Fairview Crescent and Totem Park. The pilot was successful and the data from this pilot informed appropriate public health responses.
For Winter Term 2 and Summer Session 2022, UBC scaled up wastewater monitoring. The testing plan includes sampling and analysis of four building-level sites on the UBC Vancouver campus with sample processing performed at BCCDC.
The four buildings being sampled include three student residences and one public building on campus. This gives a signal on the ‘broader’ campus community. A technician deploys and collects passive samplers three times per week, and delivers them to BCCDC for RNA extraction and SARS-CoV-2 quantification. UBC sequences positive samples to identify genomic variants of concern.
Where: Three student residences and one public building on UBC Vancouver campus.
When: 2-3 x per week starting January 2022.
How: 24-hours COVID-19 Sewer Cages (COSCa) sampler in maintenance hole.
What: Quantitative RT-PCR for SARS-CoV-2; sequencing if positive
Who: Ziels lab at UBC (sequencing), Prystajecky lab at BCCDC (sample process, RNA extraction and qRT-PCR).
Testing for SARS-CoV-2 in UBC wastewater was accomplished using a passive sampling device called a COVID-19 Sewer Cages (COSCa) sampler. The COSCa sampler is a 10cm diameter hollowed sphere with 26 holes, allowing for unrestricted flow of wastewater. An entrapment in the middle of the sampler houses an electronegative filter which captures viral particles and nucleic acid fragments as wastewater flows through the samplers.
A COSCa sampler is placed within a maintenance hole located at each UBC site. After 24 hours of passive sampling, the COSCas are sent to the British Columbia Centre for Disease Control (BCCDC) for processing. Viral particles and nucleic acids are eluted off the filter, and viruses are concentrated via centrifugal filtration. Following nucleic acid extraction, the SARS-CoV-2 E gene target is assessed by Real-Time Quantitative PCR (RT-qPCR) and normalized against a fecal indicator, Pepper Mild Mottle Virus (PPMoV).
How do we analyze wastewater genome sequencing data?
Wastewater RNA is sequenced using targeted metagenomics on all SARS-CoV-2 genome fragments present within a sample (Ct < 36). The sequence data is searched for mutations that are highly specific to VoCs and any increases / decreases in the frequency of VoC-specific mutations. The ‘frequency’ will also represent the abundance of a given VoC-specific mutation relative to all detected material at that genomic position (sums to 100% at each mutation).
The value and limits of wastewater surveillance
Testing wastewater can tell health authorities if the SARS-CoV-2 is present and how it might be changing at the same location over time. Wastewater surveillance data is used by health authorities in conjunction with other data such as testing programs and clinical reporting from hospitals to help it shape its public health policy.
- Captures the presence of SARS-CoV-2 shed by people with and without symptoms.
- Can distinguish between different variants of SARS-CoV-2.
- Can be an early indicator that the number of people with COVID-19 in a community is increasing or decreasing.
Wastewater surveillance does not:
- Identify which individuals are infected with SARS-CoV-2;
- Tell us the number of individuals who are infected with SARS-CoV-2;
- Distinguish between the number of asymptomatic individuals and individuals who are experiencing sickness.
- Tell us the number of people who are mildly ill, seriously ill or hospitalized.
Wastewater surveillance results can be impacted by:
- The number of people using the tested sewer system.
- Environmental conditions such as the amount of rainfall entering the sewage system.
For information and sampling results for the Testing for COVID -19 Virus in Wastewater for Metro Vancouver, please visit Metro Vancovuer’s website.
The following results were found as of November 2, 2022:
- Residence 1:After increasing in early September, the SARS-CoV-2 signal has remained low/undetectable to date in October.
- Residence 2: While sampling resumed on September 20, the SARS-CoV-2 signals remain low.
- Residence 3: Compared to previous weeks, the SARS CoV 2 signal has slightly increased.
- Public Building: The SARS-CoV-2 signal has remained low.
For more information or questions regarding this program, please email email@example.com.