Additionally, previous studies examining SARS-CoV-2 and Middle East respiratory virus (MERS-CoV) NAAT detection showed false-positive rates ranging from 2% to 30% (average 8%) (16,17). 1.27%;P =0.11). Age groups with highest seropositivity were 0 to 9 years (2.71%, 95% CI: 1.64 to 3.78%) followed by 20 to 29 years (1.58%, 95% CI: 1.12 to 2.04%), with the lowest rates seen in those aged 70 to 79 (0.79%, 95% CI: 0.65 to 0.93%) and >80 (0.78%, 95% CI: 0.60 to 0.97%). Compared to the seronegative group, seropositive individuals inhabited geographic areas with lower household income ($87,500 versus $97,500;P <0.001), larger household sizes, and higher proportions of people with education levels of secondary school or lower, as well while immigrants and visible minority organizations (allP <0.05). Dimenhydrinate A total of 53.7% of seropositive individuals Dimenhydrinate were potentially undetected cases with no prior positive COVID-19 nucleic acid test (NAAT). Antibodies were detectable in some individuals up to 9 weeks post positive NAAT result. This seroprevalence study will continue to inform general public health decisions by identifying at-risk demographics and geographical areas. IMPORTANCEUsing SARS-CoV-2 serology screening, we assessed the proportion of people in Alberta, Canada (human population 4.4 million) positive for COVID-19 antibodies, indicating previous infection, during the 1st two waves of the COVID-19 pandemic (prior to vaccination programs). Linking these results with sociodemographic human population data provides important information as to which groups of the population are more likely to have been Dimenhydrinate infected with the SARS-CoV-2 disease to help facilitate general public health decision-making and Dimenhydrinate interventions. We also compared seropositivity data with earlier COVID-19 molecular screening results. Absence of antibody and molecular screening were highly correlated (95% bad concordance). Positive antibody correlation with a earlier positive molecular test was low, suggesting the possibility of slight/asymptomatic illness or other reasons leading individuals from seeking medical attention. Our data focus on that the true estimate of human population prevalence of COVID-19 is likely best educated by combining data from both serology and molecular screening. KEYWORDS:SARS-CoV-2, antibody, immunology, nucleocapsid protein, serology, seroprevalence, spike protein == Intro == Shortly after the emergence of SARS-CoV-2 in Wuhan province, COVID-19 was officially declared a pandemic from the World Health Corporation on 11 March 2020. The 1st recorded case of SARS-CoV-2 illness in Canada was recorded on 25 January 2020, inside a passenger arriving in Toronto, Ontario indirectly from Wuhan (1). In the European Canadian province of Alberta, the 1st standard case was diagnosed bypost hoctesting to have occurred on 24 February 2020 in an individual arriving following travel to the Western United States (2). Since that time, Alberta offers performed over 4.2 million molecular tests for SARS-CoV-2 (as of 3 May 2021) (3). Large screening rates with quick turnaround allow for timely contact tracing of all positive instances. This improves the effectiveness of general public health interventions to identify individuals who may have been exposed to the disease and to isolate them to prevent spread within the community. Two waves of illness have been experienced in Alberta; the first wave had peak screening positivity rates of nearly 6% and occurred between March and May 2020 (4). The second wave started in October 2020, reaching a peak 1-day time positivity of 10% in mid-December 2020. Despite the high Hpt screening volume in Alberta, some proportion of instances would have been undiagnosed or asymptomatic. Serology testing with this human population provides us with additional information on the level of transmission and the concordance of serology screening within our human population after and during COVID-19 waves in the province. To further support decision-making by our general public health teams and determine the presence of unidentified populations with higher prevalence of COVID-19, residual medical blood samples from across Alberta were collected over 5-day time periods each month..