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.
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.
Third and fourth vaccine doses effectively raise antibody levels in older blood donors by mid-May: Canadian Blood Services
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.
Prevalence of SARS-CoV-2 antibodies at the beginning of the COVID-19 immunization campaign in Alberta
The proportion of individuals who tested positive for antibodies against the receptor binding domain (RBD), acquired from infection and/or vaccination, rose from 11.9% in March 2021 to 70.2% in July 2021 in Alberta.
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.
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).
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.
February’s infection-acquired seropositivity rate twice that of January 2022: Canadian Blood Services
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.
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).