ABSTRACT
The spread of SARS-CoV-2 has been studied at unprecedented levels worldwide. In jurisdictions where molecular analysis was performed on large scales, the emergence and competition of numerous SARS-CoV-2 lineages has been observed in near real-time. Lineage identification, traditionally performed from clinical samples, can also be determined by sampling wastewater from sewersheds serving populations of interest. Of particular interest are variants of concern (VOCs), SARS-CoV-2 lineages that are associated with increased transmissibility and/or severity. Here, we consider clinical and wastewater data sources to retrospectively assess the emergence and spread of different VOCs in Canada. We show that, overall, wastewater-based VOC identification provides similar in-sights to the surveillance based on clinical samples. Based on clinical data, we observed a synchrony in VOC introduction as well as similar emergence speeds across most Canadian provinces despite the large geographical size of the country and differences in provincial public health measures. In particular, it took approximately four months for VOC Alpha and Delta to contribute to half of the incidence, whereas VOC Omicron achieved the same contribution in less than one month. By quantifying the timing and rapidity of SARS-CoV-2 VOCs invasion in Canada, this study provides important benchmarks to support preparedness for future VOCs, and to some extent, for future pandemics caused by other pathogens.
ABSTRACT
Wastewater-based surveillance (WBS) of SARS-CoV-2 offers a complementary tool for clinical surveillance to detect and monitor Coronavirus Disease 2019 (COVID-19). Since both symptomatic and asymptomatic individuals infected with SARS-CoV-2 can shed the virus through the fecal route, WBS has the potential to measure community prevalence of COVID-19 without restrictions from healthcare-seeking behaviors and clinical testing capacity. During the Omicron wave, the limited capacity of clinical testing to identify COVID-19 cases in many jurisdictions highlighted the utility of WBS to estimate disease prevalence and inform public health strategies. However, there is a plethora of in-sewage, environmental and laboratory factors that can influence WBS outputs. The implementation of WBS therefore requires a comprehensive framework to outline an analysis pipeline that accounts for these complex and nuanced factors. This article reviews the framework of the national WBS conducted at the Public Health Agency of Canada to present WBS methods used in Canada to track and monitor SARS-CoV-2. In particular, we focus on five Canadian cities - Vancouver, Edmonton, Toronto, Montreal and Halifax - whose wastewater signals are analyzed by a mathematical model to provide case forecasts and reproduction number estimates. This work provides insights on approaches to implement WBS at the national scale in an accurate and efficient manner. Importantly, the national WBS system has implications beyond COVID-19, as a similar framework can be applied to monitor other infectious disease pathogens or antimicrobial resistance in the community.
ABSTRACT
ObjectivesAntigen-based rapid diagnostics tests (Ag-RDTs) are useful tools for SARS-CoV-2 detection. However, misleading demonstrations of the Abbott Panbio COVID-19 Ag-RDT on social media claimed that SARS-CoV-2 antigen could be detected in municipal water and food products. To offer a scientific rebuttal to pandemic misinformation and disinformation, this study explored the impact of using the Panbio SARS-CoV-2 assay with conditions falling outside of manufacturer recommendations. MethodsUsing Panbio, various water and food products, laboratory buffers, and SARS-CoV-2-negative clinical specimens were tested, with and without manufacturer buffer. Additional experiments were conducted to assess the role of each Panbio buffer component (tricine, NaCl, pH, and tween-20), as well as the impact of temperatures (4{degrees}C, 20{degrees}C, and 45{degrees}C) and humidity (90%) on assay performance. ResultsDirect sample testing (without the kit buffer), resulted in false positive signals resembling those obtained with SARS-CoV-2-positive controls tested under proper conditions. The likely explanation of these artifacts is non-specific interactions between the SARS-CoV-2-specific conjugated and capture antibodies, as proteinase K treatment abrogated this phenomenon, and thermal shift assays showed pH-induced conformational changes under conditions promoting artifact formation. Omitting, altering, and reverse engineering the kit buffer all supported the importance of maintaining buffering capacity, ionic strength, and pH for accurate kit function. Interestingly, the Panbio assay could tolerate some extremes of temperature and humidity outside of manufacturer claims. ConclusionsOur data support strict adherence to manufacturer instructions to avoid false positive SARS-CoV-2 Ag-RDT reactions, otherwise resulting in anxiety, overuse of public health resources, and dissemination of misinformation.
