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Because the signs and symptoms of coronavirus disease 2019 (COVID-19) may overlap with those of other respiratory pathogens, it is important to perform laboratory testing to specifically identify symptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Moreover, it is estimated that up to 40% of people with SARS-CoV-2 infection may be asymptomatic (subclinical infection) or presymptomatic, and still potentially capable of transmitting the virus to others. [1, 2] Therefore, in certain cases, individuals without obvious signs or symptoms of SARS-CoV-2 infection also require testing.
Currently, there are three basic types of tests to determine if an individual has been infected with SARS-CoV-2: viral nucleic acid (RNA) detection, viral antigen detection, and detection of antibodies to the virus. Viral tests (nucleic acid or antigen detection tests) are used to assess acute infection, whereas antibody tests provide evidence of prior infection with SARS-CoV-2. (The US Food and Drug Administration [FDA] has not authorized the use of antibody tests for the diagnosis of acute infection.)
Cell culture isolation of SARS-CoV-2 is possible, but the Centers for Disease Control and Prevention (CDC) recommends that clinical laboratories not attempt this unless it is performed in a biosafety level 3 (BSL-3)–certified laboratory.
With any type of laboratory test, the clinical accuracy or reliability depends on performance characteristics such as sensitivity and specificity, as well as the pretest probability that a person has SARS-CoV-2 infection and the prevalence of COVID-19 in the local community. Taken together, these parameters determine whether a positive or negative result should be interpreted as correct.
Créditos: Comité científico Covid