The antigens are recognised by the immune system, and specifically by antibodies. This idea underlies the rapid antigen detection tests. Many people have already had a COVID-19 antigen test, polymerase chain reaction (PCR) test, or both. Typically, a swab of the nose or throat is required for these tests.
In this post, we will examine what an antigen test is, how it functions, and its advantages and disadvantages. We contrast PCR tests with antigen assays as well.
| What is a test for antigens |
When present in the body, an antigen is a chemical that might cause an immunological reaction. It can be a bacterium, virus, toxin, chemical, or something else that comes from the outside of the body. Antigens that might trigger immunological reactions are also present in tissues and cells in the body.
Antigens are found in a bodily sample using an antigen test. As with SARS-CoV-2, the virus that causes COVID-19, these antigens may be the proteins that make up a virus.
The antigen test will show a visual change if a sample from the subject's nose or throat contains the virus. A positive result in an over-the-counter (OTC) antigen test often shows up as a line on the test, much like a positive pregnancy test.
Antigen tests have the benefit of being quick and easy. Quickly locating surface indicators on the outside of the virus is possible with an antigen test. Swabbing the nose or throat, where the virus is more likely to multiply and gather in high numbers, makes it simple to collect samples.
Results from antigen tests can also be obtained quickly. Nevertheless, they might not be as precise as PCR tests, which are the second widely used type of testing for COVID-19.
| What is the mechanism？ |
For an antigen test, a person will swab samples from their nose and throat into a solution that contains salt and soap to break down cells and particles. The liquid will then be applied to a test strip that has antibodies that are specific to the virus. As they would inside the body, antibodies on the strip will bind to the antigens in the sample.
In a positive sample, a line will be visible to show the presence of the virus or other antigen.
| Advantage |
Antigen testing have a number of advantages, such as:
delivering quick outcomes, typically within 30 minutes
being simple to do and interpret, requiring no particular training, and
being reasonably priced, ranging from $5 to $50
| Disadvantage |
An antigen test's primary risk is that it may not be as accurate as other tests.
An antigen test is often very accurate if a person is unwell and has a lot of virus in their system. The issue is that, unlike PCR tests, antigen tests do not amplify the antigens or virus they are checking for, thus they are less sensitive than PCR tests.
This means that the test may give a false-negative result if a person is in the early stages of infection and there are few antigens present in the area being swabbed.
Mixed results were observed in one study of 133 studies that assessed the reliability of 61 different antigen tests for the identification of SARS-CoV-2.
Antigen test accuracy was shown to be significantly higher in symptomatic patients (76.7%) compared to asymptomatic patients (52.5%). There is a lot of potential for error with this.
Additionally, the study revealed that more than half of the studies examined did not carry out the antigen testing in accordance with the guidelines provided by the test manufacturers. The antigen test also carries this danger. Although they might not call for a professional to administer the exam or interpret the data, they are susceptible to user mistake, which will probably reduce their accuracy.
| PCR VS. Antigen Testing |
Antigen testing are different from PCR tests in that they do more than just identify antigens in a sample.
The genetic material in a sample must be amplified for a PCR test in order for it to identify even a minute amount of the virus. By treating the sample with an enzyme to turn viral ribonucleic acid (RNA) into double-stranded DNA, they are able to accomplish this using a method known as polymerase chain reaction. It is possible to amplify the virus DNA by further processing.
| Conclusion |
Antigens in the body that trigger an immunological response, such as the production of antibodies, are found via an antigen test. Proteins from the SARS-CoV-2 virus are found in antigen testing for COVID-19.
