(Photo: Zacharie Scheurer/dpa/symbol image)Word has gotten around that many rapid tests do not reliably indicate an infection with the omicron variant.Researchers at Munich's Ludwig-Maximilians-University have therefore taken a closer look at nine commercially available rapid antigen tests with regard to their reliability.With modest results.One way to control the spread of the coronavirus is through rapid testing.However, the prerequisite for the thing to have added value is that the test is also good and does not show an incorrect result.But reliable rapid antigen tests are scarce for detecting the omicron variant, as researchers led by the virologist Oliver Keppler from the Ludwig Maximilian University of Munich (LMU) have found.The Federal Institute for Drugs and Medical Devices (BfArM) offers a list of antigen tests for direct detection of the pathogen of the Sars-CoV-2 coronavirus.The vast majority of products can therefore reliably detect a high viral load.This is especially true for the Delta variant.The scientists at the LMU, on the other hand, looked at how well nine common antigen rapid tests recognize the omicron variant.Between the end of October 2021 and the third week of January 2022, they examined 1666 corona cases that had been characterized by means of PCR and sequencing, of which 101 were omicron and 65 were delta infections.Keppler reports that the evaluations from his institute have shown that seven out of nine very frequently used rapid tests detect an omicron infection much worse than a delta infection.Result: According to the LMU, only two of the tests showed results within a reasonable range at a higher viral load.For example, tests 8 and 9 showed a sensitivity of 51.49 and 57.43, respectively, for omicron.The sensitivity is considered an important prerequisite for the reliability of the tests.This indicates the extent to which the coronavirus can be reliably detected.Even with a very high omicron viral load (with a Ct value of less than 25), the rapid tests were effective in only 31 to around 78 percent of the swab samples.With a medium viral load (with Ct values ​​between 25 and 30), the rate of omicron infections was only 0 to a good 8 percent.Almost all tests detected more than 70 percent of delta infections when the viral load was very high.With a medium viral load, the hit rate was only 0 to 28 percent.According to this, in order to achieve a 95 percent detection probability, the viral load in a smear with Omicron had to be up to 100 times higher than with Delta in some tests examined.At least there were no false positive test results, according to Keppler.For this purpose, 115 swabs with a negative PCR test were examined.The scientist demands that the unsuitability of many tests be clearly communicated and that a list of usable products be published.The LMU therefore advises wearing masks, keeping your distance and frequent ventilation, especially indoors.The Paul Ehrlich Institute is currently preparing the official list of suitable rapid corona tests, which also show a reliable result at Omikron.The Federal Ministry of Health had already announced it on January 9th.