Antibody tests, also known as serology tests, differ from the nasal- and throat-swab tests that can spot a current infection. Instead, these look for signs in the blood that the immune system had fought off an infection in the past. But there are limits to what antibodies can reveal. With other infectious diseases, antibodies signal a measure of protection against getting sick again. No one knows if that is true of this virus, or, if it is, how long such immunity might last. A positive test result with the qSARS-CoV-2 IgG/IgM test indicates that antibodies to SARS-CoV-2 were detected, and the patient has potentially been exposed to COVID-19. When IgM antibodies are present, they can indicate that a patient has an active or recent infection with SARS-CoV-2. IgG antibodies develop later following infection, and generally do not begin to appear until 14-21 days after infection. When IgG antibodies are present it, often indicates a past infection but does not exclude recently infected patients who are still contagious, especially if detected with IgM antibodies. Since most patients do not know the exact time when they contracted the virus, the combining both IgM and IgG tests provides a much higher test sensitivity and test specificity. It is unknown how long IgM or IgG antibodies to SARS-CoV-2 will remain present in the body after infection and if they confer immunity to infection.