SARS-CoV-2 seroprevalence among blood donors after the first COVID-19 wave in Canada.

Case detection underestimates the burden of the COVID-19 pandemic. Following the first COVID-19 wave, we estimated the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among blood donors across Canada. This serial cross-sectional study was conducted between May 9 and July 21, 2020 from blood donors donating at all Canadian Blood Services locations. We used the Abbott Architect assay to detect SARS-CoV-2 IgG antibodies from retention plasma. Seroprevalence was standardized to population-level demographics and assay characteristics were adjusted using the Rogan-Gladen equation. Results were stratified by region, age, ethnicity, ABO groups, and quantiles of material and social deprivation indices. Temporal trends were evaluated at 2-week intervals. Univariate and multivariate logistic regression compared SARS-CoV-2 reactive to non-reactive donors by sociodemographic variables. Overall 552/74642 donors, had detectable antibodies, adjusted seroprevalence was 7.0/1000 donors (95% CI; 6.3, 7.6). Prevalence was differential by geography, Ontario had the highest rate, 8.8/1000 donors (7.8, 9.8), compared to the Atlantic region 4.5/1000 donors (2.6, 6.4); adjusted odds ratio (aOR) 2.2 (1.5, 3.3). Donors that self-identified as an ethnic minority were more likely than white donors to be sero-reactive aOR 1.5 (1.2, 1.9). No temporal trends were observed. Worldwide, blood services have leveraged their operational capacity to inform public health. While >99% of Canadians did not show humoral evidence of past infection, we found regional variability and disparities by ethnicity. Seroprevalence studies will continue to play a pivotal role in evaluating public health policies by identifying trends and monitor disparities.

Saeed S ，Drews SJ ，Pambrun C ，Yi QL ，Osmond L ，O'Brien SF ... -  《-》

Progression and Predictors of SARS-CoV-2 Antibody Seroreactivity In US Blood Donors.

The second largest US blood center began testing for antibodies to SARS-CoV-2, the etiologic agent of Coronavirus Disease-2019 (COVID-19) to identify potential COVID-19 Convalescent Plasma (CCP) donors and encourage blood donation. We report the non-vaccine seroprevalence of total immunoglobulin directed against the S1 spike protein of SARS-CoV-2 in our donors. Unique non-CCP donor sera from June 01to December 31, 2020 were tested with the Ortho VITROS Anti-SARS-CoV-2 total immunoglobulin assay (reactive: signal-to-cutoff (S/C) ≥ 1). Multivariate regressions including age, sex, race-ethnicity, ABO, RhD, highest education level, donor experience, regional collection center and drive type factors were conducted to identify demographics associated with the presence of antibodies and with S/C values. Unique donors (n = 523,068) showed an overall seroprevalence of 6.12% over 7 months, with the highest prevalence in December 2020 around Lubbock, TX (24.3%). In a subset of donors with demographic information (n = 394,470), lower odds of antibody reactivity were associated with female sex, non-Hispanic White or Asian race/ethnicity, age ≥ 65, graduate education, blood Group O, and history of blood donation. In reactive donors (n = 24,028), antibody signal was associated with male sex, race/ethnicity other than non-Hispanic White, low educational attainment, age 16-17 years and geographic location. Seroprevalence continues to grow in US blood donors but varies significantly by region. Temporal trends in reactivity may be useful to estimate effectiveness of public health measures. Before generalizing these data from healthy donors to the general population, rates must be corrected for false-positive test results and adjusted to match the wider US demography.

Vassallo RR ，Dumont LJ ，Bravo MD ，Hazegh K ，Kamel H ... -  《-》

Estimating SARS-CoV-2 Seroprevalence in Canadian Blood Donors, April 2020 to March 2021: Improving Accuracy with Multiple Assays.

Tuite AR ，Fisman D ，Abe KT ，Rathod B ，Pasculescu A ，Colwill K ，Gingras AC ，Yi QL ，O'Brien SF ，Drews SJ ... -  《Microbiology Spectrum》

Seroprevalence of anti-SARS-CoV-2 IgG antibodies in the staff of a public school system in the midwestern United States.

Lopez L ，Nguyen T ，Weber G ，Kleimola K ，Bereda M ，Liu Y ，Accorsi EK ，Skates SJ ，Santa Maria JP Jr ，Smith KR ，Kalinich M ... -  《PLoS One》

Seroprevalence of SARS-CoV-2 Infection in Portugal in May-July 2020: Results of the First National Serological Survey (ISNCOVID-19).

Kislaya I ，Gonçalves P ，Barreto M ，Sousa R ，Garcia AC ，Matos R ，Guiomar R ，Rodrigues AP ，ISNCOVID-19 Group ... -  《Acta Medica Portuguesa》