Emergence and spread of SARS-CoV-2 variants of concern in Canada: a retrospective analysis from clinical and wastewater data.

BACKGROUND: 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-2lineages have 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. Variants of concern (VOCs) and SARS-CoV-2 lineages associated with increased transmissibility and/or severity are of particular interest. METHOD: Here, we consider clinical and wastewater data sources to assess the emergence and spread of VOCs in Canada retrospectively. RESULTS: We show that, overall, wastewater-based VOC identification provides similar insights to the surveillance based on clinical samples. Based on clinical data, we observed 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. CONCLUSION: In particular, it took approximately four months for VOC Alpha and Delta to contribute to half of the incidence. In contrast, VOC Omicron achieved the same contribution in less than one month. This study provides significant benchmarks to enhance planning for future VOCs, and to some extent for future pandemics caused by other pathogens, by quantifying the rate of SARS-CoV-2 VOCs invasion in Canada.

Emergence of SARS-CoV-2 Delta Variant and Effect of Nonpharmaceutical Interventions, British Columbia, Canada.

In British Columbia, Canada, initial growth of the SARS-CoV-2 Delta variant was slower than that reported in other jurisdictions. Delta became the dominant variant (>50% prevalence) within ≈7-13 weeks of first detection in regions within the United Kingdom and United States. In British Columbia, it remained at <10% of weekly incident COVID-19 cases for 13 weeks after first detection on March 21, 2021, eventually reaching dominance after 17 weeks. We describe the growth of Delta variant cases in British Columbia during March 1-June 30, 2021, and apply retrospective counterfactual modeling to examine factors for the initially low COVID-19 case rate after Delta introduction, such as vaccination coverage and nonpharmaceutical interventions. Growth of COVID-19 cases in the first 3 months after Delta emergence was likely limited in British Columbia because additional nonpharmaceutical interventions were implemented to reduce levels of contact at the end of March 2021, soon after variant emergence.

Risk of Infection and Sepsis in Pediatric Patients with Traumatic Brain Injury Admitted to Hospital Following Major Trauma.

Head injury accounts for 29% of all traumatic deaths in children. Sepsis is significantly associated with an increased risk of mortality in adult traumatic brain injury patients. In the pediatric population, this relationship is not well understood. The objective of this study was to compare the proportion of pediatric traumatic brain injury (TBI) patients and trauma patients without brain injury (NTBI) who developed sepsis or any infection during their index hospital admission. We performed a retrospective study of all trauma patients <18 years of age, admitted to trauma centres in Alberta, Canada from January 1, 2003 to December 31, 2012. Patients who died within 24 hrs of trauma (n = 147) and those with burns as the primary mechanism of injury (n = 53) were excluded. Hospital admission data for the remaining 2556 patients was analyzed. 1727 TBI patients and 829 NTBI patients were included. TBI was associated with lower odds of developing sepsis (OR 0.32 95% CI 0.14-0.77 p = 0.011). TBI was not found to be independently associated with developing any infectious complication after adjusting for confounding by Injury Severity Score (OR 1.25 95% CI 0.90-1.74 p = 0.180). These relationships warrant further study.