Berlin, 15. November 2021 – PCR, antibody and antigen tests: they all aim to detect a possible infection with the SARS-CoV-2 coronavirus. But how do the tests differ and when are they used??
When to get tested for SARS-CoV-2?
Who should be tested when for SARS-CoV-2? And how conclusive are the tests actually?? Prof. Dr. Martin Scherer, Chairman of the German Society for General Medicine (DEGAM), provides answers to the following questions.
PCR test: the reliable Add to info basket
The PCR test (abbreviation for engl. polymerase chain reaction test) use a biochemical process called the polymerase chain reaction. Scientists use this procedure to examine genetic material – for example, whether certain hereditary diseases are present. It can also be used to detect pathogens such as viruses or bacteria. This is because they also contain a form of genetic material. The SARS-CoV-2 virus is a so-called ribonucleic acid (RNA for short). In the PCR test, this RNA is amplified, stained with special dyes and thus made visible. This can be used to determine whether and how much RNA was present in a person’s body. A PCR test is a direct detection for the SARS-CoV-2 coronavirus. It detects corona infections very accurately and reliably.
How it works: For the PCR test, a sample is taken from the mouth, nose or throat using a swab. A biochemical procedure (PCR) is then used in the laboratory to determine whether this sample contains the RNA of the SARS-CoV-2 virus. The test result is usually available after 24 to 48 hours, in urgent cases even earlier.
Antigen test: the quick test for everyday life Add to info basket
Faster than the PCR test is the antigen test. This is often also called Quick test indicates. The antigen test is also a direct detection for the coronavirus SARS-CoV-2. The virus is identified by means of certain proteins (so-called. antigens) detected. In people who carry the SARS-CoV-2 virus, these proteins are found in the nose, mouth and throat. The function of an antigen test is similar to a pregnancy test. There are two display windows: one window indicates whether the test worked or not. The other window shows the test result. Below these windows is a test strip with antibodies. These antibodies recognize the virus proteins. Then a colored line appears in the second control window. Although the test must be performed by trained personnel, laboratory analysis is not necessary. This is why the antigen test is more suitable for everyday use than the PCR test. This must be used to check if the antigen test is positive.
This is how it works: As with the PCR test, a swab is taken from the mouth or throat for the antigen test. This is applied to the test. The test is positive if a colored line appears in both display windows. The result can be read after a few minutes.
Antigen self-test: practical detection at home Add to info basket
Self-tests for self-testing function like rapid antigen tests. They are even easier to use, so that they can also be used by lay people at home.
How it works: Most self-tests do not require a deep nasal or throat swab. The samples are z. B. taken by a swab in the front nasal area or in the oral cavity. The result can be read after approx. Read off 15 to 20 minutes by two strokes on the viewing window. If the result is positive, it must be checked by a PCR test. Because the antigen rapid tests for self-testing have a higher error rate compared to PCR tests.
The self-tests are available in pharmacies, drugstores and supermarkets. When buying online, make sure that the products have passed the test by the Paul Ehrlich Institute. This can be seen on the corresponding list of the Federal Institute for Drugs and Medical Devices.
Corona warning app red? Right to PCR test
Good to know: Anyone who has received a red warning (status "increased risk") via the Corona Warning app is entitled to a free PCR or antigen test at a public testing center. This is in the "Questions and answers to the National Test Strategy of the Federal Government.