Figure 4.

Antigenemia may add value to screening or diagnostic testing strategies in specific clinical scenarios: eg, (A) as a screening strategy for hospitalized patients without coronavirus disease (COVID) symptoms where only antigenemia-positive individuals receive nasopharyngeal swab (NPS) testing. This may allow for universal asymptomatic screening at lower costs than NPS screening while reducing unnecessary isolation of patients with nonviable ribonucleic acid and providing advantages over abandoning asymptomatic screening altogether. (B) Antigenemia may be a useful adjunct test in individuals with COVID-compatible symptoms but confusing clinical history, such as recent verified severe acute respiratory syndrome coronavirus 2 (SC2) infection in the preceding weeks but beyond 10 days from initial diagnosis. Absent antigenemia in this scenario should favor consideration of an alternative diagnosis, whereas presence of antigenemia should be interpreted in the context of the history timelines, reverse-transcription polymerase chain reaction (RT-PCR) cycle threshold value, deep respiratory tract sampling when indicated, and radiographic characteristics to aid the diagnostic impression. Each of these applications warrant further investigation. CBC, complete blood count.