What is the most appropriate test to diagnose COVID-19 in an individual presenting with suggestive symptoms?
What the research says:
Diagnostic testing for COVID-19 includes:
|Clinical Situation||Appropriate Test||Testing for||Sensitivity (to identify disease)||Specificity (to identify no disease||Clinical sample||Time to result|
|Symptomatic individual||Laboratory-based DNA amplification||Presence of viral RNA||High||High||Nasopharyngeal/ oropharyngeal swab||15 minutes to >2 days*|
|Laboratory-based antigen testing||Presence of viral antigens||Moderate||High||Nasopharyngeal/ oropharyngeal swab||15 minutes to >2 days*|
|Lateral flow (point-of-care) test||Presence of viral antigens||Low to moderate**||High||Nasopharyngeal/ oropharyngeal swab or finger prick blood sample||15–30 minutes|
*Dependent on local laboratory capacity
**Dependent on factors such as for how long somebody has been infected
Antibody testing can be used to indicate past infection, but is not an indicator of current infection.
What this means for your clinical practice:
Confirmation of a suspected diagnosis of COVID-19 infection requires a positive laboratory-based DNA- or antigen-based test. Where laboratory testing is not an option, point-of-care testing can be utilised using a lateral flow test although there is a higher risk of a false negative result.
Supporting references and databases:
Centers for Disease Control and Prevention. Using Antigen Tests. December 2020. Available at: https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html#table1. Accessed January 2021.
European Centre for Disease Prevention and Control. Diagnostic testing and screening for SARS-CoV-2. Available at: https://www.ecdc.europa.eu/en/covid-19/latest-evidence/diagnostic-testing. Accessed October 2020.
Green K, et al. What tests could potentially be used for the screening, diagnosis and monitoring of COVID-19 and what are their advantages and disadvantages. Available at: https://www.cebm.net/covid-19/what-tests-could-potentially-be-used-for-the-screening-diagnosis-and-monitoring-of-covid-19-and-what-are-their-advantages-and-disadvantages/#:~:text=PCR%20is%20a%20very%20common,the%20virus%20causing%20COVID%2D19. Accessed October 2020.
WHO. Advice on the use of point-of-care immunodiagnostic tests for COVID-19. Available at: https://www.who.int/news-room/commentaries/detail/advice-on-the-use-of-point-of-care-immunodiagnostic-tests-for-covid-19. Accessed October 2020.