* Clinical management of COVID-19 (Interim Guidance), World Health Organization [99].
** If antigen detection would be incorporated into the testing algorithm, how this needs to be done depends on the sensitivity and specificity of the antigen test and on the prevalence of SARS-CoV-2 infection in the intended testing population. For more information see section below on “Rapid diagnostic tests based on antigen detection” and the specific guidance Interim guidance on antigen-detection in diagnosis of SARS-CoV-2 infection using rapid immunoassays [5].
*** Continued clinical suspicion can, for example, be the absence of another obvious etiology, the presence of an epidemiological link, or suggestive clinical finding (e.g. typical radiological signs).
**** The selection of specimen type will depend on the clinical presentation, see section “Specimens to be collected”. Increasing the number of samples tested will also increase the sensitivity of testing for COVID-19. More than two samples might be needed on some occasions to detect SARS-CoV-2 [73]. ***** For interpretation of serology, see section “Implementation and interpretation of antibody testing in the clinical laboratory”. Serology cannot be used as a standalone diagnostic for acute SARS-CoV-2 infections and clinical management.