If you’re wondering about what the difference is between a Covid test and an antigen test, you’re in the right place. This article will break down the differences between the two tests and help you to choose which one is best for you. You’ll learn what makes them different, how they work, and how to get the most accurate results.

• Sensitivity

The sensitivity of a Covid virus test and antigen test can vary depending on the specimen type. When the viral load is high, the sensitivity of the antigen test increases. However, when the viral load is low, the sensitivity of the antigen test may decline. This is because the assay is not as sensitive to detecting residual viral nucleic acid.

During the first week after the onset of symptoms, the sensitivity of the COVID-19 test is higher than it is in patients who have not developed symptoms. Symptomatic individuals have a sensitivity of between 60 and 72 percent. On the other hand, asymptomatic individuals have a sensitivity of between 12 and 15 percent.

In order to maximize the sensitivity of a Covid virus test, it is best to perform a second test at least one or two days after a negative test. If the second test is positive, the person is likely infected.

• Specificity

The sensitivity of an antigen test depends on a number of factors. These factors include the type of assay, the type of specimen collected, and the timing of the test.

For example, the sensitivity of a rapid antigen test, which detects SARS-CoV-2 RNA using a polymerase chain reaction, is lower than the sensitivity of an RT-PCR test. This has been noted in studies.

Studies also indicate that the sensitivity of an antigen test improves with increasing viral RNA in upper respiratory specimens. In certain cases, the sensitivity of an antigen test increases to over 90 percent. However, there is little information on the specificity of these tests.

Although the sensitivity of an antigen test may differ from study to study, it is important to note that the sensitivity of an antigen test is higher during the first week of illness. Sensitivity also depends on the quality of sampling. A positive test may be interpreted as a negative in low-risk situations.

• Cross-reactivity

Most serologic tests that detect a patient’s immune response to a disease are sensitive enough to provide information about an individual’s immune status. However, the specificity of these tests depends on the type of assay used and the timing of the specimen.

One way to detect a SARS-CoV-2 infection is to use an antigen test. Antigen tests are less sensitive than nucleic acid tests (NAATs). But, they are useful when NAATs are not available. Also, they can be useful when there is a low probability of an infection.

Some antigen tests, such as enzyme-linked immunosorbent assays, are more accurate than others. Other types of tests, such as lateral flow immunoassays, have lower sensitivity. The specificity of these tests varies from manufacturer to manufacturer.

Another type of test that detects an individual’s immune response to a disease is a binding antibody test. It requires specialized equipment and trained laboratory personnel. Specificity is typically below 99 percent.