Fig. 2.

Biases due to misclassification by SARS-CoV-2 antibody tests. The sensitivity of a SARS-CoV-2 antibody test is the probability the test is positive given an individual has been infected with the virus, while the specificity is the probability of a negative test given an individual has not been infected with SARS-CoV-2. Test performance is imperfect; low sensitivity can result in an estimate of cumulative incidence that is too low (as individuals with prior infection are misclassified as negative), and low specificity can result in an estimate of cumulative incidence that is too high (as individuals without prior infection are misclassified as positive). Outline color represents prior SARS-CoV-2 infection status (red for prior infection, blue for no prior infection). The annotation (“+” or “−”) indicates the result of a test for SARS-CoV-2 antibodies. Bold outlines indicate individuals who are misclassified by the test