2024-02-08 18:40:03
Cough, runny nose and sore throat: Many people are currently sick. But it is often unclear what exactly the trigger is. Is it a cold or the flu? But that can be found out – with a test that detects more than just Corona or with the help of medical professionals.
There are sniffles and coughs everywhere. Because just in time for the start of the year, the wave of respiratory infections has really picked up speed. If someone has symptoms, they quickly say: Don’t worry, it’s not Corona. I did a test. But what is it then? This statement cannot really be reassuring, because other infectious diseases such as influenza – the flu – or RS viruses are also highly contagious and can be dangerous.
Self-tests for flu and RSV are now legal
The Corona self-tests for at home, which can provide a little more clarity, are well-known and popular. However, many people don’t even know that such test strips also exist for other pathogens. Self-tests for influenza A and B have been allowed to be sold since last spring. Previously, the determination of whether it was real flu was reserved for doctors because it is a reportable illness. But since a change to the so-called Medical Devices Tax Ordinance, the test has also been available for laypeople.
The Federal Ministry of Health’s justification for easing the regulation stated that the population has been using self-tests as a matter of course since the Covid-19 pandemic and that there is no reason that this should be any different with influenza. In addition, the ministry says it assumes that people will either go straight to the doctor after a positive test result or isolate themselves and avoid contact. The legal situation is currently identical to Corona and HIV self-tests, which are also available for home use.
Rapid antigen test can detect influenza A and B
The so-called quadruple tests have now become established in practice. These are combination tests that can test for corona, influenza A and B as well as the respiratory syncytial virus (RSV) at the same time. In principle, they work in the same way as the rapid antigen tests for Corona: You take a nasal swab, mix it with the liquid provided and drip a few drops onto the test cassette. This is slightly different from the well-known Corona self-tests. Instead of one control panel, there are two stripes, sometimes even three next to each other. It takes at least 15 minutes for the result, even for the combination tests. They are now available from several manufacturers in pharmacies and drugstores.
The self-test reacts to the residues of proteins typical of the viruses. As with Corona, it is significantly less sensitive than a PCR test, which detects the genetic material of a virus. If there are enough residues in the swab for the rapid test, they bind to antibodies that are on the test strips and a line or a positive test result is displayed. With multiple testing, this can even mean multiple positive results in the rare case that someone is actually infected with several of the viruses at the same time.
Experts have mixed feelings about the combination test
However, you shouldn’t feel safe with a negative test, because it can of course also be false negative (or false positive). In addition, incorrect implementation can always lead to an incorrect result, for example if the swab was not taken deep enough in the nasopharynx. In any case, if the test result is positive, those affected should first consult a doctor.
A quadruple test that reveals in one fell swoop which infectious disease you have or whether it might be a harmless cold sounds tempting, of course. But there are also critical voices. For example, virologist Bodo Plachter from Mainz University Medicine points out that lay tests are fundamentally more unreliable than laboratory-based tests such as the PCR test. With the new tests, there is also the fact that there are still no sensible and independent studies on them.
Multiple tests work in the same way as Corona self-tests. Image rights: IMAGO / Panthermedia
Problem: Rapid flu test only detects the virus very late
The virologist Ulrike Protzer from the Technical University of Munich, on the other hand, outlined technical reasons to the BR as to why the multiple tests make little sense. “The rapid tests are designed to cause cells to break and viral proteins to be released. There is no longer any amplification mechanism involved. That means: you need a very high viral load for such a rapid test to respond. You often don’t have that, especially at the beginning of an infection. “That’s not so relevant for Corona because the virus produces very high titers. But for influenza, for RSV, for other viruses, that’s a very relevant limitation,” she said.
This means that the multiple test for RSV and influenza only becomes positive when everything is already too late. And in the course of recovery, when the sick person may no longer be contagious, the test would still be positive.
If you have any symptoms or suspected cases, go to the doctor’s office
Anyone who has a positive combination test should contact their family doctor’s office. Because here it may be necessary to test again. In the case of the flu, for example, the direct detection of influenza viruses must be reported according to the Infection Protection Act (IfSG). A doctor would therefore have to diagnose the disease.
In general, doctors can arrange a PCR test for infectious diseases. According to the Robert Koch Institute, it is up to the doctor to decide when to test. The Saxony Association of Statutory Health Insurance Physicians states that testing can be carried out in practice “at the doctor’s discretion”.
Doctors should only test if the infection threatens to have serious consequences
The Thuringia Association of Statutory Health Insurance Physicians is a little more specific: “In principle, sick people should only be tested for SARS-CoV-2 or for other pathogens such as influenza if consequences can be derived from the result (e.g. protection of risk groups) or the test result has an influence on the treatment of the patient.”
So there is no testing on request because you would like to know exactly what you have. But the KV explains that there are not only test kits for self-tests, but also numerous laboratories that offer diagnostic tests for self-payers.
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