Respiratory diseases: What rapid antigen tests can offer

For Professor Dr. Manfred Schubert-Zsilavecz of Pharmaceutical Chemistry at the University of Frankfurt, Pharmacies are the appropriate place to find out about point-of-care (POC) rapid tests, such as the one on to inform about Covid-19 . With ever-new variants emerging, to which the As the coronavirus continues to mutate, the question naturally arises whether old antigen tests still work at all.

"The tests also work with new variants," said Schubert-Zsilavecz at the recent Expopharm in Düsseldorf states, "The mutations do not affect test sensitivity." This is because the emergence of new variants of SARS-CoV-2 is caused by mutations in the spike protein. However, self-tests detect the virus's nucleoside protein (N-protein) via an antigen-antibody reaction. This protein is less prone to mutations, which is why older tests may still show a positive result.

Regarding SARS-CoV-2, we now live in a highly immunized population, and unlike at the beginning of the pandemic, the maximum viral load during an infection usually only occurs some time after the onset of symptoms – on average after four days. Therefore, the sensitivity of tests at the onset of symptoms is low, according to the pharmacist. The US Food and Drug Administration The FDA therefore advises that if the initial test is negative but symptoms are present, a second test should be performed 48 hours later.

In addition to rapid SARS-CoV-2 tests, antigen tests for influenza A and B viruses, as well as RSV – including combination tests – are also available. The following quadruple tests for self-administration are widely used: CorDx Combo4 test, fluorecare® test, and Solmira® test. Following an amendment to the Medical Devices Distribution Ordinance, these tests have been permitted to be dispensed in pharmacies for approximately two years; previously, this was only allowed for rapid COVID-19 and HIV tests. According to the manufacturers, the quadruple tests are only suitable for children aged two and older.

But be aware: While these self-tests for influenza and RSV viruses may be sold to laypersons, they cannot currently be administered in pharmacies. The planned pharmacy reform could change this . The reason: As notifiable diseases, the diagnosis of influenza and RSV is the responsibility of a doctor. Therefore, it is advisable to remind customers when dispensing the tests that positive results and further steps must be discussed with a doctor. In principle, the quadrivalent tests work similarly to those for coronaviruses, although the exact procedure varies depending on the product.