The latest CITF-funded report from Canadian Blood Services suggests that seroprevalence due to infection was 82.68% in December 2023, in line with the 82.97% found in November 2023. Consistent with previous reports, the percentage of younger donors (ages 17-24) who had infection-acquired seroprevalence was the highest of all donor age groups.

The latest CITF-funded report from Canadian Blood Services suggests that seroprevalence due to infection was 83% in November 2023, up slightly from 81.6% in October 2023. This increase was not statistically significant.

A CITF-funded study, published in Cureus, examined the impact of different dosing intervals between the first two COVID-19 mRNA vaccines. Intervals longer than 38 days, compared to a short interval of less than 30 days, resulted in higher levels of SARS-CoV-2 anti-spike antibodies.

The latest CITF-funded report from Canadian Blood Services suggests that seroprevalence due to infection is now stable among Canadian blood donors at approximately 80%.

The latest CITF-funded report from Canadian Blood Services suggested that seroprevalence due to infection was 80.1% among Canadian blood donors at the end of September 2023. This increased slightly from the 79.0% seroprevalence observed in August 2023.

The latest CITF-funded report from Canadian Blood Services suggested that seroprevalence due to infection was 79.03% among Canadian blood donors in August 2023.

The latest CITF-funded report from Canadian Blood Services suggests that seroprevalence due to infection was stable at 80% among Canadian blood donors by the end of July.

The latest CITF-funded report from Canadian Blood Services suggests that the 80% mark in estimated infection-acquired seroprevalence among Canadian adults has now been reached.

The latest CITF-funded report from Canadian Blood Services suggests that the 80% mark in estimated infection-acquired seroprevalence among Canadian adults has now been reached.

The latest CITF-funded seroprevalence report from Canadian Blood Services shows that approximately 79.6% of adult blood donors had infection-acquired seroprevalence in May, which is similar to April (79.4%).

Among Canadian Blood donors, the infection-acquired seroprevalence continued to rise in the month of November 2022, to 71%, up from 67.4%, at the end of October.

In a paper published in Microbiology Spectrum, CITF-funded researchers, including at Canadian Blood Services, showed that infection-acquired immunity to SARS-CoV-2 varied, in 2021, by age, region, racial group, the neighbourhoods in which people lived and whether they were materially or socially deprived (had fewer contacts). Interestingly, these factors were not consistent throughout all provinces and regions.

Consistent with the continued prevalence of the Omicron variants (predominantly BA.4, BA.5 and BA.5 subvariants), infection-acquired seropositivity continues to increase among blood donors, up to 65.41% by the end of September, from 60% in the last week of August. These data come from Canadian Blood Services.

This study, published in Microbiology Spectrum and carried out by CITF-funded researchers Drs. Steven Drews and Sheila O’Brien of Canadian Blood Services, characterized the neutralization capacity and the breadth of protection against SARS-CoV-2 and its variants of concern (Alpha, Beta, Gamma, and Delta).

A study carried out by SeroTracker (a CITF-funded project), in partnership with the World Health Organization, found global SARS-CoV-2 seroprevalence (due to infection or vaccination or both) was 45.2% by end of June 2021.

Using various serological assays in parallel on the same set of samples can produce inconsistent results. A solution is to use composite reference standards and latent class analysis to help decipher true seropositivity.

Published in Frontiers in Public Health, the CARTaGENE research team, based at the Research Center at the Centre Hospitalier Universitaire Sainte-Justine and part of the CITF-funded CanPATH study, found that vaccination hesitancy among adults in Quebec was correlated with education levels, age and other socio-demographic determinants.

In a paper published in Microbiology Spectrum, researchers with Canadian Blood Services (CBS) point to the changing patterns of infection-acquired and vaccine-induced seroprevalence, observed between January and November 2021.

A paper now published in JCI Insight by CITF-funded researchers Drs. Anne-Claude Gingras, Tania Watts, and Vinod Chandran of the University of Toronto provides evidence of the need for a third dose of mRNA vaccine in patients with immune-mediated inflammatory diseases (IMID).

The HostSeq platform, established in April 2020, is a national collaboration of population-based studies investigating the genetic risk factors behind SARS-CoV-2 infection and health outcomes associated with it.

Consistent with the ongoing transmission of the Omicron variant, infection-acquired seropositivity increased in the blood donor community gradually throughout May, from 36.71% at the end of April to 48.96% at the end of May, according to data from Canadian Blood Services.

As part of the COVID-19 Occupational Risks, Seroprevalence and Immunity among Paramedics (CORSIP) study, CIFT-funded researchers Drs. Brian Grunau and David Goldfarb (University of British Columbia) did not find that, during the pre-Omicron waves, paramedics were at higher risk of catching SARS-CoV-2 than a control group of blood donors.

A preprint, not yet peer-reviewed, from a CITF-funded study, suggests that the chances of adults getting infected with SARS-CoV-2 was lower in the school setting than it was in the community, even during the first Omicron wave.

A CITF-funded study, led by Drs. Brian Grunau and David Goldfarb and Pascal Lavoie (University of British Columbia), and Sheila O’Brien and Steven Drews of Canadian Blood Services, and published in Open Forum Infectious Diseases, tested the sensitivity of the Roche anti-SARS-CoV-2 nucleocapsid assay.

With the continued transmission of the Omicron variant in Canada, infection-acquired seroprevalence increased again within the blood donor community, from 46.3% at the end of May to 50.7% by the end of June.

The latest serosurvey conducted by Héma-Québec estimates that 45.3% of adults in Quebec developed infection-acquired antibodies to SARS-CoV-2 between December 2021 and June 2022, up from 27.3% in mid-March 2022.

In a preprint, not yet peer-reviewed, CITF-funded researchers developed a novel approach to detect SARS-CoV-2 anti-nucleocapsid antibodies. The ratio-based approach had a 95.2% sensitivity among both previously vaccinated and previously infected donors compared with 63.3% for the conventional approach.

Due to continued transmission of the newer Omicron variants (BA.4 and BA.5) in Canada, infection-acquired seropositivity increased within the blood donor community, from 50.7% at the end of June to 54% by the end of July, with a modest week-to-week change throughout July.

In a letter published in RMD Open, CITF-funded researchers found that SARS-CoV-2 antibody levels and T cell responses increased following a third dose of vaccine in immunocompromised patients. Drs. Vinod Chandran, Anne-Claude Gingras, and Tania Watts (University of Toronto) showed that 92% of COVID-naïve patients with immune-mediated inflammatory disease (IMID) showed anti-spike and anti-RBD antibody levels that were greater than convalescent individuals (those recovering from COVID-19 infection).

In a systemic review published in BMJ Global Health, Dr. Rahul Arora (University of Calgary) and the CITF-funded SeroTracker team estimates that seroprevalence in Africa (due to infection or vaccination) was 65.1% in July-September 2021.

A new study, published in Microbiology Spectrum from the CITF-funded Canadian Blood Services (CBS) team led by Drs. Sheila O’Brien and Steven Drews, characterizes the ability of a new immunoassay to specify the concentration of neutralizing antibodies against SARS-CoV-2 in blood plasma.

Omicron and its subvariants (BA.4 and BA.5) continued to spread in Canada in August. By the last week of August, 60% of blood donors had infection-acquired seropositivity, up from 56.5% at the end of July.

In a study published in the International Journal of Epidemiology, the CITF-funded SeroTracker team, including Dr. Rahul Arora (University of Calgary), contributed to showing that only 70% of individuals invited to participate in seroprevalence studies actually enrolled.

In a publication in Clinical Proteomics led by Drs. Brent Richards and Guillaume Butler-Laporte (McGill University), CITF funded researcher Dr. Daniel Kaufmann (Université de Montréal) and Dr. Vincent Mooser (McGill University, former director of the Biobanque québécoise de la COVID-19 (BQC19)) determined that severe COVID-19 is associated with significant changes in 69 immune-related proteins.

A report published in the Annals of the New York Academy of Sciences, prepared with the participation of the CITF-funded Serotracker team, presents the outcomes of the April 2022 Keystone symposium on the successes and challenges of the COVID-19 pandemic. Rahul Arora (University of Calgary) participated as a representative of the CITF-funded SeroTracker initiative.

A systematic review carried out by the CITF-funded SeroTracker team, released in preprint, and not yet peer reviewed, reported that third-party or independent evaluations from manufacturers found that the manufacturers appear to overstate the sensitivity and specificity of their serological assays targeting SARS-CoV-2.

A preprint, not yet peer-reviewed, from a CITF-funded study led by Dr. Sonia Anand (McMaster University) focused on the South Asian community to demonstrate that understanding factors such as community dynamics, language, and cultural context can help build vaccine confidence and acceptance among diverse population groups.

According to Canadian Blood Services data published in Viruses, infection-related seroprevalence increased with the emergence of the Omicron SARS-CoV-2 variant from September 2021 to June 2022.

The gap between the rates of COVID-19 infection and vaccination among racialized and non-racialized Canadians continues to exist, as does the gap between Canadians from lower- and higher-income neighbourhoods. The CITF-funded Canadian Blood Services Serosurveillance Study has released its latest report for the month of May 2021. While the latest data show that the […]

Remarkably, nearly all Canadian Blood Services blood donors sampled in November tested positive for antibodies against the SARS-CoV-2 spike protein. While this was mainly due to vaccination with at least one vaccine dose, seroprevalence from a prior infection with COVID-19 stood at 5.1%, higher than what was seen in previous months. In a subset […]

The latest report from Canadian Blood Services, covering the early days of the Omicron wave, shows that, notwithstanding the nearly universal presence of anti-SARS-CoV-2 antibodies among blood donors, the number of donors who had antibodies due to prior infection rose. Key findings: The proportion of donors with evidence of a prior infection was 6.4% […]

Infection-acquired seropositivity increased throughout February 2022, averaging out to 23.7% for the month - double January’s rate of 12.1% - according to data from Canadian Blood Services.

The latest data from Canadian Blood Services show the rapid increase in infection-induced immunity began slowing by mid-March. The data show infection-acquired seropositivity increased moderately between the end of February and mid-March, up to 27.5% from 25.3%.

A recent serosurvey conducted by Héma-Québec estimates that 27.4% of adults in the province developed infection-acquired antibodies to SARS-CoV-2 between January and mid-March 2022, during the first Omicron wave.

Consistent with the ongoing transmission of the Omicron variant, infection-acquired seropositivity increased in the blood donor community gradually throughout March, from 27% to 30%.

Blood donors between 17 and 24 years old have persistently experienced the highest seropositivity rate from infection. Mid-April data from the Canadian Blood Services show that a majority (52%) in this age group had evidence of infection-acquired antibodies (antibodies targeting the nucleocapsid protein).

Consistent with the ongoing transmission of the Omicron variant, infection-acquired seropositivity increased among blood donor throughout April, from 33% at the beginning of the month to 40% by the end.

Consistent with the ongoing transmission of the Omicron variant, infection-acquired seropositivity increased in the blood donor community gradually through the beginning of May, from 40% at the end of April to 46% by mid-May, according to the latest data from Canadian Blood Services.

In its latest report, Canadian Blood Services revealed the toll of Omicron’s spread through mid-February 2022. Not only did 22.7% of all blood donors experience a prior SARS-CoV-2 infection, but this rate represented a 35% jump during the 22-day sampling period (January 24 – February 15).

The latest Canadian Blood Services (CBS) report, from October 2021, indicates that 98% of blood donors sampled had antibodies to SARS-CoV-2. This number is largely driven by immunization with at least one vaccine dose, as infection-acquired seroprevalence stayed low, at 4.3%. Results also reveal a downward trend in the mean levels of antibodies across […]

May 26, 2021

The continued persistence of SARS-CoV-2 infections in predominantly unvaccinated individuals has meant a continued need for therapeutics to treat those hospitalized with COVID-19.

96% of Canadian blood donors have evidence of SARS-CoV-2 antibodies, primarily due to vaccination, a rate that has increased from 91% in June and 95% in July. This according to Canadian Blood Services’ 13th seroprevalence report, covering data from August 2021. Nonetheless, targeted efforts to alleviate infection burden and promote vaccine uptake are still […]

The latest results from the Canadian Blood Services’ monthly serosurvey indicate that 95% of blood donors sampled in July 2021 had antibodies against SARS-CoV-2, acquired predominantly through vaccination. Not only did vaccine-induced seroprevalence increase among all sociodemographic groups and across all geographic regions, but infection-acquired seroprevalence dropped compared to June 2021. Donors identifying as […]

The month of June saw many Canadians rolling up their sleeves for a COVID-19 vaccine. The latest results from the Canadian Blood Services’ serosurvey reflect this, with vaccine-induced seroprevalence soaring to 86% across Canada (excluding the Territories and Quebec), up from 60% the month prior. Most importantly, the gap in vaccine coverage among socioeconomic […]

A recent preprint, not yet peer reviewed, by CITF Testing Working Group members Dr. Anne-Claude Gingras from University of Toronto, and Dr. Steven Drews from Canadian Blood Services, compared multiple assays and concluded ‘Made-in-Canada’ ones performed well.

Blood donation organizations to provide important assessment of how long immunity lasts   NEWS RELEASE   MONTREAL, May 27, 2021 — Results from the latest Canadian Blood Services and Héma-Québec studies, which together cover all 10 provinces, confirm that from coast-to-coast, Canada’s overall levels of seroprevalence due to SARS-CoV-2 infection remained very low earlier […]

Serosurveillance survey shows SARS-CoV-2 infections growing much faster in poorer neighbourhoods and amongst racialized populations Results from the latest Canadian Blood Services/COVID-19 Immunity Task Force (CITF) collaborative nine-province seroprevalence study confirm that the pandemic is increasingly affecting poorer neighbourhoods and racialized populations. The inequalities in risk in getting COVID-19 were identified early in the pandemic […]

View a table of Canadian seroprevalence estimates from Canadian Blood Services for May 2020 to January 2021. Links to full reports available as well.

Results from CBS’s initial survey, conducted between May 9th and July 21st, 2020 showed that 552 of the 74,642 donors tested had detectable antibodies, which gave an adjusted seroprevalence of 7.7 per 1000 donors.

Canadian Blood Services and the CITF’s collaborative nine-province SARS-CoV-2 seroprevalence study for October thru November suggests that 1.5 per cent of healthy Canadians had been exposed to SARS-CoV-2. The highest levels were recorded in Western Canada but mass national vaccination remains only route to achieving herd immunity.