SARS-CoV2 seroprevalence in Placer county, Preliminary Report (submitted 6/29/21; data collected 10/20-4/21)

CA-FACTS (The Californians Fighting Against Coronavirus Together Study), Placer County is a collaboration between Stanford University and the County of Placer, with data collected from October 2020 to April of 2021. A preliminary report was submitted to the county in June 2021, before all data had been received and cleaned. We found that among a representative sample of county residents who both provided a blood spot for testing and completed a survey on demographics and behaviors, seroprevalence increased from 1.2% in January 2021 to 43.6% in March 2021, due in part to an increasing proportion of the population being vaccinated. The data used for this preliminary report are provided here, along with a data dictionary. A revised updated and cleaned final dataset and final report will be posted when available.