From BZ/dpa
Everyone would probably want a negative result in the rapid corona test. If one is positive and the next negative, the joy should be less. How do the different results come about?
At home, the shock is great: the rapid corona test is positive. But what if things look different in the test center and the result of the rapid antigen test is negative here? Instead of relief, there is often uncertainty: Which result is correct – and what is the best way to behave?
“If the test results and the clinical symptoms do not give a uniform picture, you should do a third test after twelve hours,” advises the chairman of the Professional Association of German Laboratory Doctors (BDL), Andreas Bobrowski.
And even if the obligation to isolate is aimed at people who have been proven to have tested positive: rely on personal responsibility. That means: avoid contact in the time between the test results. After all, “it could well be that the test you did at home was the right one,” says Bobrowski.
Incorrect results due to application errors
According to the BDL chairman, different antigen test results can be caused by errors in the implementation and acceptance of the test. If the nasal swab is not done thoroughly at home or at the testing center and not enough material gets to the swab, an infection may not be detected.
If the quick test has been in a car heated up by the sun for too long, this could also falsify the result. The tests have not lost anything in the refrigerator either.
Different qualities of the rapid tests used can also explain the different results. Bobrowski therefore advises that when you do another quick test at home, you should make sure that it is included in the common EU list of COVID-19 antigen tests – and thus meets specified quality criteria.
PCR test for symptoms
According to the Robert Koch Institute (RKI), false-positive rapid test results can occur if the antigen rapid test reacts to another germ that occurs in the nose: Staphylococcus aureus. Interactions between a bacterial protein and the detection antibodies of the rapid test are responsible for this.
A lab worker prepares test tubes for a PCR test (archive photo) Photo: scg cul vco
For Bobrowski, the “silver bullet” is then to secure the rapid test results with a PCR test. If you suffer from the corresponding symptoms, your family doctor can arrange for this. Despite a negative result in the rapid test center, the health insurance companies then assume the costs for patients with statutory health insurance.
A PCR test can also be falsely negative or falsely positive, for example if the sample was contaminated during transport to the laboratory. With a hit rate of 98 percent, PCR tests are initially more reliable than rapid antigen tests.