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

Abstract

ObjectivesGathering 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.DesignThis cross-sectional study included online surveys that collected sociodemographic and COVID-19 vaccine receipt information, and an at-home DBS collection kit.SettingBritish Columbia (BC), Canada.ParticipantsEligible participants were aged 25–69 years and residents of BC.Primary outcome measureSARS-CoV-2 anti-spike IgG antibody detection in unvaccinated individuals. Adjusted incidence rate ratios (aIRR) explored factors associated with seropositivity.ResultsSARS-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.ConclusionsSARS-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.

Higher Perceived Stress during the COVID-19 pandemic increased Menstrual Dysregulation and Menopause Symptoms

“…It is possible that the mechanism behind stress and menstrual changes also involves glucocorticoid receptors in the endometrium 48 . Although SARS-CoV-2 infection and vaccines use can also disrupt reproductive cycles in the short term 7,10 , we do not believe this influenced our findings because we found that the seroprevalence of previous infection in this cohort was 2.9% 49 and vaccines were not widely available to the general BC population at the time of this survey. There are limitations to our study.…”

High pre‐Delta and early‐Omicron SARS‐CoV‐2 seroprevalence detected in dried blood samples from Kinshasa (D.R. Congo)

“…36,39 Still, the available commercial assays do not include DBS as an approved sample type and there is limited real-world comparative performance evidence. 40,41 This study aims to improve our understanding of SARS-CoV-2 seroprevalence in Sub-Saharan Africa…”

“…DBS have proven useful for the serological study of different viral infections (HIV, HCV, HBV) in these regions 32,33 and since the start of the pandemic researchers have confirmed DBS are comparable to serum samples 34–38 and present good performance on various commercial platforms 36,39 . Still, the available commercial assays do not include DBS as an approved sample type and there is limited real‐world comparative performance evidence 40,41 …”