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Diagnosing the COVID-19 viral infection relies on two major methodologies: identification of the viral RNA using polymerase chain reaction analysis, and serological immunoassays that detect viral-specific antibodies (IgM and IgG). Screening for the viral RNA uses nasopharyngeal swabs and identifies the active virus during clinical disease. As the clinical symptoms resolve the active virus disappears and screening tests become negative. Viral antibodies, however, develop in response to the virus and remain after the active virus is no longer present. IgM appears within 5-7 days of the infection and parallels the active viral infection. It disappears shortly after the virus disappears. The IgM antibody assay can therefore serve as a check on the viral RNA assay and catch any false-negative cases of which a number have been reported. The IgG antibody appears around day 14 after the infection has begun and as symptoms resolve. The IgG can then determine if there has been a previous infection with or without clinical symptoms. This is important because it indicates an immunity to future COVID-19 infections.