1. This test can only detect SARS-CoV-2 antigen in human saliva only, not other specimen.

2. If the procedure is done incorrectly, it may cause inaccurate results.

3. False negative results happen if:

• • The concentration of antigen in a specimen is below the detection limit of the test.
  • The specimen was not collected or transported properly.

4. Positive results do not rule out co-infections with other pathogens.

Therefore, due to its limitation in detection range and sensitivity, RTK-Antigen test is used as a screening test and RT-PCR is used as confirmatory test to define a COVID-19 case.