Conclusion
Based on the real-world data described here, Standard ™ Q COVID-19 Ag has the disadvantage of low diagnostic performance relative to the RT-qPCR; its sensitivity varies with sampling time and with the amount of viral nucleic acid contained in the sample. This test is best used for subjects with high viral load and when done early after COVID-19 symptom onset. Pending its application in large scale, our data recommend against using this test alone for COVID-19 diagnosis. This RAT, therefore, has no benefit in replacing or reducing the use of RT-qPCR assay for COVID-19 diagnosis at the time of pandemic.