Seropositivity of SARS-CoV-2 in an unvaccinated cohort in British Columbia, Canada: a cross-sectional survey with dried blood spot samples.

Gathering population-based data on prevalence of SARS-CoV-2 infection is vital to the public health response and planning. Current seroprevalence data in BC are limited with respect to considerations of how socioeconomic and demographic factors, such as age, sex, gender, income, identifying as a visibility minority and occupation, are related to SARS-CoV-2 antibody detection due to infection-acquired immunity. We aimed to estimate the SARS-CoV-2 seropositivity in a cohort of British Columbians, using at-home self-collected dried blood spot (DBS) samples. This cross-sectional study included online surveys that collected sociodemographic and COVID-19 vaccine receipt information, and an at-home DBS collection kit. British Columbia (BC), Canada. Eligible participants were aged 25-69 years and residents of BC. SARS-CoV-2 anti-spike IgG antibody detection in unvaccinated individuals. Adjusted incidence rate ratios (aIRR) explored factors associated with seropositivity. SARS-CoV-2 serology was performed on a total of 4048 unvaccinated participants 25-69 years of age who submitted DBS samples taken from November 2020 to June 2021. A total of 118 seropositive cases were identified, for an estimated overall seropositivity of 2.92% (95% CI 2.42% to 3.48%). Participants identifying as a visible minority had a higher seropositivity, 5.1% vs 2.6% (p=0.003), compared with non-visible minority participants. After adjustment by age and sex, identifying as a visible minority (aIRR=1.85, 95% CI 1.20 to 2.84) remained the only significant factor associated with SARS-CoV-2 antibody detection in this cohort of unvaccinated individuals. SARS-CoV-2 seropositivity in the BC population due to infection-acquired immunity was low. Seropositivity indicated that among those unvaccinated, visible minority communities have been most impacted. Continued monitoring of SARS-CoV-2 serology due to both infection-acquired and vaccine-acquired immunity will be vital in public health planning and pandemic response.

Racey CS ，Booth A ，Albert A ，Smith LW ，Krajden M ，Murray MCM ，Côté HCF ，Gottschlich A ，Goldfarb DM ，Sadarangani M ，Galea LAM ，Kaida A ，Brotto LA ，Ogilvie GS ... -  《BMJ Open》

Performance of Immunoglobulin G Serology on Finger Prick Capillary Dried Blood Spot Samples to Detect a SARS-CoV-2 Antibody Response.

Nikiforuk AM ，McMillan B ，Bartlett SR ，Márquez AC ，Pidduck T ，Kustra J ，Goldfarb DM ，Barakauskas V ，Sinclair G ，Patrick DM ，Sadarangani M ，Ogilvie GS ，Krajden M ，Morshed M ，Sekirov I ，Jassem AN ... -  《Microbiology Spectrum》

Pre-Vaccine Positivity of SARS-CoV-2 Antibodies in Alberta, Canada during the First Two Waves of the COVID-19 Pandemic.

Charlton CL ，Nguyen LT ，Bailey A ，Fenton J ，Plitt SS ，Marohn C ，Lau C ，Hinshaw D ，Lutsiak C ，Simmonds K ，Kanji JN ，Zelyas N ，Lee N ，Mengel M ，Tipples G ... -  《Microbiology Spectrum》

Factors associated with SARS-CoV-2 infection in unvaccinated children and young adults.

Silverberg SL ，Shulha HP ，McMillan B ，He G ，Lee A ，Márquez AC ，Bartlett SR ，Gill V ，Abu-Raya B ，Bettinger JA ，Cabrera A ，Coombs D ，Gantt S ，Goldfarb DM ，Sauvé L ，Krajden M ，Morshed M ，Sekirov I ，Jassem AN ，Sadarangani M ... -  《BMC INFECTIOUS DISEASES》

Assessment of SARS-CoV-2 Seropositivity During the First and Second Viral Waves in 2020 and 2021 Among Canadian Adults.

Tang X ，Sharma A ，Pasic M ，Brown P ，Colwill K ，Gelband H ，Birnboim HC ，Nagelkerke N ，Bogoch II ，Bansal A ，Newcombe L ，Slater J ，Rodriguez PS ，Huang G ，Fu SH ，Meh C ，Wu DC ，Kaul R ，Langlois MA ，Morawski E ，Hollander A ，Eliopoulos D ，Aloi B ，Lam T ，Abe KT ，Rathod B ，Fazel-Zarandi M ，Wang J ，Iskilova M ，Pasculescu A ，Caldwell L ，Barrios-Rodiles M ，Mohammed-Ali Z ，Vas N ，Santhanam DR ，Cho ER ，Qu K ，Jha S ，Jha V ，Suraweera W ，Malhotra V ，Mastali K ，Wen R ，Sinha S ，Reid A ，Gingras AC ，Chakraborty P ，Slutsky AS ，Jha P ，Ab-C Study Investigators ... -  《JAMA Network Open》