Since the Corona virus began to spread, we have learned a lot of new terms. Antigens and antibodies, Sars-CoV-2 and COVID-19. We have also been given various options to test whether you are or have been infected with Coronavirus or COVID-19. Tests with tops in the nose and tests through blood tests. How do you know which test is right for you and which is which? How do they work and what information do they provide?
There are currently two basic types of tests for COVID-19 or SARS-CoV-2 which are the official name of the virus. There is a diagnostic test that shows if you are currently infected and a test that shows if you have already been infected with COVID-19. Let’s take a closer look at which test provides which information.
Antigen & Antibody Tests – Diagnosed Coronavirus Tests
The antigen test is the test that shows if you are currently infected with COVID-19. The antibody test, on the other hand, shows if you have already been infected with SARS-CoV-2 or COVID-19 and your immune system has developed antibodies to the virus.
- Antigen test, often called rapid test or Corona Test. This test detects protein fragments specific for Coronavirus. The Corona test gives a quick answer, already within 15 minutes. This is the test taken by swab in the back of the nasal wall. The antigen test is very reliable as it has a Sensitivity of 96.52% and a Specificity of 99.68%.
- The antibody test, on the other hand, is taken by a stick in the finger or a capillary blood sample. This test is also very reliable as it has a sensitivity of 99.99% and a specificity of 99.80%.
This type of diagnostic test is often called a “rapid test” because the treatment time is much faster than a PCR test.
What are PCR tests?
What then is a PCR test? PCR testing is considered the “gold standard” in the pursuit of tracking SARS-CoV-2. The PCR test can detect RNA, genetic material, which is specific for the virus and can thus detect the virus within a few days after infection. Even on those who have no symptoms of COVID-19. However, these tests take longer to get answers to and are most often used to rule out a so-called false negative test result with rapid tests.
This makes the reliable so-called rapid tests more effective to use to prevent the spread of COVID-19. In cases where you have symptoms but test negative in an antigen test then a PCR test may be in place to rule out that you would have tested false negative.
An antigen test is performed by taking a sample from the throat or almost. The places where viruses like to accumulate and where they thrive. The test looks for the proteins that come from the COVID-19 virus. What are called antigens.
A positive antigen test result can correctly diagnose a COVID-19 infection. If either test is negative, it does not necessarily mean that you are not infected. It is possible to get a false negative answer when the test sample does not have enough virus proteins, especially if you have just become infected. This is because the incubation period for COVID-19 can be up to two weeks. If you have previously been infected with COVID-19 and recovered, an antigen test may not be able to detect the virus. When an infection disappears, the antigens from the body are eliminated. To find out if you have been infected before, you will need to take an antibody test.
Antibody tests cannot detect an ongoing infection but test whether the body’s immune system has developed antibodies to COVID-19. That is, if you have already been infected with COVID-19. Antibody tests can detect antibodies even if you have been infected many months ago.
It is important to remember that if you are infected, it can take from several days up to a couple of weeks before the body’s immune system has developed antibodies and the antibody test can detect it. Therefore, it is recommended to wait up to 14 days after the first symptoms are detected before taking an antibody test.
It is still not entirely clear whether the development of antibodies to SAR-Co V-2 means that you can not be re-infected. Some studies suggest that some protection is being developed against a new COVID-19 infection. The Swedish Public Health Agency states that a positive result indicates protection against re-infection within a limited period of time. The period of time that you are protected against severe COVID-19 symptoms is currently estimated to be up to six months from the time you have received your test result.
Antibody tests are important for the Swedish Public Health Agency to get an overview of the infection situation and how often asymptomatic infections occur.
You can read more about our antigen and antibody tests here and you are warmly welcome to contact us for more information!