The serological IgG assay that Sonora Quest offers is validated to be highly specific for SARS-CoV-2. For this validated assay, a positive result indicates a high likelihood of prior infection and that a person has mounted an immune response. Different assays target different viral proteins. Some assays detect antibodies to nucleocapsid and others detect spike proteins. Spike and nucleocapsid assays are highly correlated with each other. As additional research is conducted and vaccines potentially emerge, Sonora Quest will tailor SARS-CoV-2 testing offerings to be informed by evolving information.