摘要: COVID-19, caused by SARS-CoV-2, led to an unprecedented global health crisis. As the majority of people infected with SARS-CoV-2 have no or only mild symptoms, many cases aren’t captured by direct testing. However, it is important to establish the true spread of the virus by identifying how many people have been exposed. Detection of anti–SARS-CoV-2–specific antibodies in blood samples can help us understand how the pandemic is evolving over time. We developed a sensitive and specific assay that performs 1,024 measurements in parallel. To enable decentralized blood sample collection, the method can detect antibodies in a small drop of blood obtainable by finger pricking, and the blood can be collected and shipped with a simple, low-cost blood glucose test strip. All study data are included in the article, [ SI Appendix ][1], and [Datasets S1][1] and [S2][1]. [1]: https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2025289118/-/DCSupplemental