covid-19 testing
There are two different types of tests; diagnostic tests and antibody tests. A diagnostic test shows an active coronavirus infection. There are two types of diagnostic tests; a molecular PCR test that detects the virus's genetic material and a rapid antigen test which detects specific proteins in the virus. The other type of test, an antibody test looks for antibodies made by the immune system in response to a specific viral threat. They can take several days or even weeks to develop. This test should not be used to diagnose covid-19 but to show if a patient has been infected in the past.
PCR testing
This is a molecular test showing a current coronavirus infection and is taken with a nasal swab. It’s the most accurate test while the results take longer. Upon receival of the specimen, results are found within a few hours and typically reported within 24 hours. They may be reported within hours or at least the same day for unique circumstances. When confirming an antigen test with a PCR test, specimens for each test should be collected within 48 hours of each other.
antigen testing
This is a rapid test that shows a result in as little as 15 minutes and is also taken with a nasal swab. It has a higher chance of missing an active infection as it's not as sensitive as a PCR test. Results are also highly accurate but there’s a greater chance of a false negative result which doesn't rule out an infection. With this in mind, an antigen test may need to be supplemented with a PCR test for confirmation. This test performs best early in the stages of infection when the viral load is generally highest. That means it's best for patients showing symptoms of covid-19 or with known recent exposure to it.
antibody testing
Antibody tests, or serology tests are taken with a blood sample and may provide quick results but should not be used to diagnose an active infection. Antibody tests only detect antibodies the immune system develops in response to the virus; they don’t detect the virus itself. It can take days or weeks to develop enough antibodies to be detected in a test. A positive result can mean a patient has developed antibodies that can provide immunity to the infection. However, it’s not a guarantee and it's unknown how long the antibodies remain in the body following infection.
