General population studies

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.

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.

Research carried out at the CITF-funded Biobanque québécoise de la COVID-19 (BQC19), published in PLOS Genetics by Drs. Guillaume Butler-Laporte, Brent Richards, and Vincent Mooser (McGill University), showed that those with a rare deleterious variant (disease causing variant) in the SARS-CoV-2 sensor toll-like receptor TLR7 gene (on chromosome X in the host) were associated with a 5.3-fold increase in severe disease.

A preprint, not yet peer-reviewed, from CITF-funded researchers Dr. Sharmistha Mishra, Ms. Huiting Ma, Dr. Sharon Straus (University of Toronto) and their Wellness Hub team, indicated that public health interventions implemented since the first wave of the COVID-19 pandemic did not sufficiently address income-related health disparities.

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.

Consistent with the continued prevalence of Omicron variant its subvariant, infection-acquired seropositivity increased among blood donors to 62.4% by mid-September, up from 60% in the last week of August. These data come from Canadian Blood Services.

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.

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.

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.

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.