Table 1.

Advantages and disadvantages of diagnostic tests for SARS-CoV-2 infection in patients with COVID-19-like symptoms, according to clinical scenario

	Aim	Advantages	Disadvantages
Within 2 weeks after symptom onset
Molecular test (ideally nasopharyngeal or nasal swabs)	To detect viral RNA (preferred test)	Provides the most sensitive and specific means of confirming a clinical diagnosis	Expensive; requires specialised skills and instruments; testing is not at point of need; results can take longer than 24–48 h
Antigen rapid detection test (ideally nasopharyngeal or nasal swabs)	To detect viral protein if molecular testing is not available or the results are delayed	Can provide results within 15–20 min; can be done outside of a laboratory setting with minimal training; cheaper and faster to manufacture than molecular tests	Not as sensitive as molecular tests; more difficult to assure quality, especially with self-tests, compared with laboratory-based tests; if a patient tests negative, it is necessary to collect another sample for molecular testing
More than 2 weeks after symptom onset
Molecular test, antigen rapid detection test, and antibody test	To establish a late or retrospective diagnosis by using antibody tests if molecular and antigen rapid tests are both negative	Can provide results in 15–20 min if a rapid antibody test or within 24 h if a laboratory-based assay	Antibody tests can be non-specific and cause false-positive results; can be difficult to determine if seropositivity is vaccine-induced or natural
Patient has persistently negative test results but there is a high index of suspicion based on clinical presentation or other criteria (eg, chest CT scan findings)
Repeat molecular or antigen rapid detection test using a lower respiratory tract specimen (eg, sputum or bronchioalveolar lavage sample, or tracheal aspirate and blood for an antibody test) and antibody test	To confirm a clinical diagnosis	Confirms clinical diagnosis if the lower respiratory tract specimen is positive; enables retrospective diagnosis of past or recent infection if the antibody test is positive	Antibody tests can be non-specific and cause false-positive results