Interpretation of laboratory results for COVID-19 diagnosis, 6 May 2020
Pan American Health Organization
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Etiological confirmation of COVID-19 virus (SARS-CoV-2) infection can only be made by laboratory tests. In general, the currently available assays for COVID-19 can be classified into two groups: • The first group (virological tests) includes tests that can detect the presence of the components of the virus (genetic material or antigens). These tests can confirm the diagnosis of patients with symptoms compatible with COVID-19, detect infections in populations with high-risk of infection (such as health workers) or severity (hypertension, diabetes, obesity, cardiovascular history, chronic respiratory, immunosuppression, cancer, etc.), and assess whether an individual recovered from COVID-19 may still be infectious. • The second group of tests (serological) detects antibodies (IgM or IgG) generated as part of the individual's immune response against the SARS-CoV-2 virus, that is, they indicate previous or ongoing contact. The immunity (protection) conferred by the antibodies is still under investigation. Once sufficient evidence is available, serological tests would be, together with direct virus detection, an essential tool in the development of strategies that allow relaxation of current public health measures.