FIGURE 1.

Key assumptions in simulation of net benefit. (A) The timing of transmission events both from cases and from their direct contacts, in absence of intervention, follows a nonuniform distribution relative to the time of symptom onset in the index case. Shading illustrates that different amounts of transmission are preventable after earlier (light shading) versus later (dark shading) diagnosis. (B) The simulated viral burden in upper respiratory diagnostic specimens at symptom onset is log-normally distributed across a simulated population. This may be conceptualized in terms of genome copies on a quantitative reverse-transcriptase PCR (units shown on y axis) or antigen copies (assumed to vary in proportion to genome copies during acute illness). (C) After an initial period of maximal detection, the simulated sensitivity of antigen testing declines on a similar timeline as infectivity, and sensitivity of PCR declines more slowly.