Related Experiment Video

Updated: Jul 19, 2025

Author Spotlight: Advancements in Multiplex Detection of Respiratory Viruses

Author Spotlight: Advancements in Multiplex Detection of Respiratory Viruses

Published on: November 10, 2023

The evolution of SARS-CoV-2 seroprevalence in Canada: a time-series study, 2020-2023

Tanya J Murphy¹, Hanna Swail¹, Jaspreet Jain¹

¹COVID-19 Immunity Task Force (Murphy, Swail, Jain, Evans, Oxlade, Mazer, Buckeridge), School of Population and Global Health, McGill University, Montréal, Que.; Department of Community Health and Epidemiology (Anderson, Behl), University of Saskatchewan; Saskatchewan Health Authority (Anderson), Population Health, Saskatoon, Sask.; Department of Molecular Genetics (Awadalla), University of Toronto; Department of Computational Biology (Awadalla), Ontario Institute for Cancer Research; Centre for Global Health Research (Brown), Unity Health Toronto and University of Toronto, Toronto, Ont.; Public Health Laboratory (Charlton, Hinshaw, Tipples), Alberta Precision Laboratories, University of Alberta Hospital; Department of Laboratory Medicine and Pathology (Charlton, Tipples), and Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alta.; Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital (Colwill, Gingras), Sinai Health System, Toronto, Ont.; Canadian Blood Services (Drews); Department of Laboratory Medicine and Pathology (O'Brien, Pambrun, Drews), University of Alberta, Edmonton, Alta.; Department of Molecular Genetics (Gingras, Skead), University of Toronto; Centre for Global Health Research (Jha), Unity Health Toronto and University of Toronto, Toronto, Ont.; Public Health Laboratory (Kanji), Alberta Precision Laboratories, Foothills Medical Centre, and Section of Medical Microbiology (Kanji), Department of Pathology and Laboratory Medicine, and Division of Infectious Diseases, Department of Medicine, University of Calgary, Calgary, Alta.; Ontario Health Study (Kirsh, Skead), Ontario Institute for Cancer Research; Department of Molecular Genetics (Kirsh, Skead), and Dalla Lana School of Public Health (Kirsh), University of Toronto, Toronto, Ont.; Roy Romanow Provincial Lab (Lang), Saskatchewan Health Authority; College of Medicine (Lang), University of Saskatchewan, Saskatoon, Sask.; Department of Biochemistry, Microbiology and Immunology (Langlois), and Centre for Infection, Immunity and Inflammation (Langlois), University of Ottawa, Ottawa, Ont.; Division of Infectious Diseases-Regina (Lee), University of Saskatchewan; Saskatchewan Health Authority (Lee), Saskatoon, Sask.; Medical Affair and Innovation (Lewin), Héma-Québec, Montréal, Que.; Departments of Epidemiology and Community Medicine (O'Brien), and Pathology and Laboratory Medicine (Pambrun), Faculty of Medicine, University of Ottawa, Ottawa, Ont.; Department of Mathematics & Statistics (Stephens), McGill University, Montréal, Que.; Department of Medical Microbiology (Stein, Van Caeseele), University of Manitoba, and Cadham Provincial Laboratory, Winnipeg, Man.; School of Population and Global Health (Evans), McGill University; The Research Institute of the McGill University Health Centre (Mazer, Buckeridge), Montréal, Que.

CMAJ : Canadian Medical Association Journal = Journal De L'Association Medicale Canadienne

|August 14, 2023

Abstract

Background:

During the first year of the COVID-19 pandemic, the proportion of reported cases of COVID-19 among Canadians was under 6%. Although high vaccine coverage was achieved in Canada by fall 2021, the Omicron variant caused unprecedented numbers of infections, overwhelming testing capacity and making it difficult to quantify the trajectory of population immunity.

Methods:

Using a time-series approach and data from more than 900 000 samples collected by 7 research studies collaborating with the COVID-19 Immunity Task Force (CITF), we estimated trends in SARS-CoV-2 seroprevalence owing to infection and vaccination for the Canadian population over 3 intervals: prevaccination (March to November 2020), vaccine roll-out (December 2020 to November 2021), and the arrival of the Omicron variant (December 2021 to March 2023). We also estimated seroprevalence by geographical region and age.

Results:

By November 2021, 9.0% (95% credible interval [CrI] 7.3%-11%) of people in Canada had humoral immunity to SARS-CoV-2 from an infection. Seroprevalence increased rapidly after the arrival of the Omicron variant - by Mar. 15, 2023, 76% (95% CrI 74%-79%) of the population had detectable antibodies from infections. The rapid rise in infection-induced antibodies occurred across Canada and was most pronounced in younger age groups and in the Western provinces: Manitoba, Saskatchewan, Alberta and British Columbia.

Interpretation:

Data up to March 2023 indicate that most people in Canada had acquired antibodies against SARS-CoV-2 through natural infection and vaccination. However, given variations in population seropositivity by age and geography, the potential for waning antibody levels, and new variants that may escape immunity, public health policy and clinical decisions should be tailored to local patterns of population immunity.

More Related Videos

Live Imaging and Quantification of Viral Infection in K18 hACE2 Transgenic Mice Using Reporter-Expressing Recombinant SARS-CoV-2

Live Imaging and Quantification of Viral Infection in K18 hACE2 Transgenic Mice Using Reporter-Expressing Recombinant SARS-CoV-2

Published on: November 5, 2021

Detection of SARS-CoV-2 Neutralizing Antibodies using High-Throughput Fluorescent Imaging of Pseudovirus Infection

Detection of SARS-CoV-2 Neutralizing Antibodies using High-Throughput Fluorescent Imaging of Pseudovirus Infection

Published on: June 5, 2021

Related Concept Videos

Viral Mutations

Viral Mutations

A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material...

Prevalence and Incidence

Prevalence and Incidence

In statistical epidemiology and health sciences, two essential metrics—prevalence and incidence—are fundamental for understanding disease dynamics within a population. These measures enable public health officials, epidemiologists, and researchers to assess the burden of diseases, allocate resources effectively, and design impactful public health policies and interventions.
Prevalence indicates the proportion of individuals in a population who have a specific disease or health...

Single Nucleotide Polymorphisms-SNPs

Single Nucleotide Polymorphisms-SNPs

A single nucleotide polymorphism or SNP is a single nucleotide variation at a specific genomic position in a large population. It is the most prevalent type of sequence variation found in the human genome. Point mutations that occur in more than 1% of the population qualify as SNPs. These are present once every 1000 nucleotides on an average in the human genome. Replacement of a purine with another purine (A/G) or a pyrimidine with another pyrimidine (C/T) is known as a transition. In contrast,...

Steps in Outbreak Investigation

Steps in Outbreak Investigation

In the ever-evolving field of public health, statistical analysis serves as a cornerstone for understanding and managing disease outbreaks. By leveraging various statistical tools, health professionals can predict potential outbreaks, analyze ongoing situations, and devise effective responses to mitigate impact. For that to happen, there are a few possible stages of the analysis:

Principles of Disease Surveillance

Principles of Disease Surveillance

Disease surveillance is the systematic collection, analysis, and interpretation of health data essential to the planning, implementation, and evaluation of public health practice. This process integrates data dissemination to entities responsible for preventing and controlling disease, injury, and disability. Surveillance systems provide crucial information for action, helping public health authorities make informed decisions to manage and prevent outbreaks, ensure public safety, optimize...

Causality in Epidemiology

Causality in Epidemiology

Causality or causation is a fundamental concept in epidemiology, vital for understanding the relationships between various factors and health outcomes. Despite its importance, there's no single, universally accepted definition of causality within the discipline. Drawing from a systematic review, causality in epidemiology encompasses several definitions, including production, necessary and sufficient, sufficient-component, counterfactual, and probabilistic models. Each has its strengths and...

Articles linked to this work by shared authors, journal, and citation graph.

Mitotic single-stranded DNA suppression by DDIAS.

Molecular cell·2026

Preserved SARS-CoV-2 T-cell responses despite impaired humoral immunity in children with profound B-cell lymphopenia.

NPJ vaccines·2026

Proteomic investigation of signaling dynamics: from static maps to network rewiring.

Bioscience reports·2026

SARS-CoV-2 infection in female sex workers from Nairobi, Kenya early in the COVID-19 pandemic: Seroincidence and behavioural associations.

PloS one·2026

Findings from comprehensive genome sequencing in the Canadian population: Results from the GENCOV Study.

Genetics in medicine open·2026

SCM-1/SCAMP Maintains Microdomain Boundaries and Cargo Sorting within the Endosomal System.

bioRxiv : the preprint server for biology·2026

See all related articles