Diagnostic performance of rapid antigen tests for SARS-CoV-2 transmission risk based on cycle threshold values in the emergency department.

The RAT might be a rapid screening tool for detecting patients with the infectiousness of SARS-CoV-2. However, considering the low NPV, it is challenging to depend only on a negative test result from an antigen test to terminate quarantine. Clinicians should consider additional factors, such as the duration of symptoms and the immunocompromised state, for SARS-CoV-2 transmission.