Multiplexed, quantitative serological profiling of COVID-19 from a drop of blood by a point-of-care test

Heggestad, Jacob T.; Kinnamon, David S.; Olson, Lyra B.; Liu, Jason; Kelly, Garrett; Wall, Simone A.; Fontes, Cassio M.; Joh, Daniel Y.; Hucknall, Angus M.; Pieper, Carl; Naqvi, Ibtehaj A.; Chen, Lingye; Que, Loretta G.; Oguin, Thomas; Nair, Smita K.; Sullenger, Bruce A.; Woods, Christopher W.; Sempowski, Gregory D.; Kraft, Bryan D.; Chilkoti, Ashutosh

Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage the COVID-19 pandemic. Here, we report on a microfluidic, multiplexed POC test that can profile the antibody response against multiple SARS-CoV-2 antigens—Spike S1 (S1), Nucleocapsid (N), and the receptor binding domain (RBD)—simultaneously from a 60 μL drop of blood, plasma, or serum. We assessed the levels of anti-SARS-CoV-2 antibodies in plasma samples from 19 individuals (at multiple time points) with COVID-19 that required admission to the intensive care unit and from 10 healthy individuals. This POC assay shows good concordance with a live virus microneutralization assay, achieved high sensitivity (100%) and specificity (100%), and successfully tracked the longitudinal evolution of the antibody response in infected individuals. We also demonstrated that we can detect a chemokine, IP-10, on the same chip, which may provide prognostic insight into patient outcomes. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed in the fight against COVID-19 by democratizing access to laboratory quality tests.