Biology of SARS-CoV-2: Detection | HHMI BioInteractive Video

[crickets] [footsteps] [cymbal plays] [chime] [music plays] There are several ways to test whether someone has been infected with SARS-CoV-2. Some tests can detect if you have an active infection, or an infection that is happening right now, and others can detect if you’ve had an infection in the past and recovered. To determine whether you have an active infection, doctors can look for the presence of the virus in your body. One test uses RT-PCR, or reverse transcriptase polymerase chain reaction, to look for pieces of the virus’s RNA genome. A swab is taken of the inside of your nose or throat to collect cells or saliva in which the virus is likely replicating.

00:54 - If the virus’s RNA is in your cells, it will be detected by the PCR test and give a positive test result. Another test for detecting an active infection looks for pieces of viral proteins recognized by the immune system, called antigens. If viral antigens are in your sample, they will be detected by the antigen test and give a positive result. But what if you’ve already recovered and no longer have the virus in your body? In this case, a blood sample is taken to test for the presence of specific types of antibodies that recognize the virus. Antibodies are proteins produced by your body’s immune system to fight off infections.

01:39 - Studying people who have antibodies to the virus can help scientists understand where a virus is spreading and how our immune system fights the virus. None of these tests are foolproof. Viral RNA, viral antigens, and antibodies are all produced at different times during an infection, and they won’t always be detected. And, some tests are also less sensitive than others, resulting in false negatives. Doctors may use a combination of tests, or repeat tests at different times, if they’re uncertain. [music plays] .